diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java
index 06ac54617ae6..b96b47c5a785 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java
@@ -30,8 +30,8 @@ public class Actions {
           // disable classloader check as Avro may cache class/object in the serializers.
           .set(CoreOptions.CHECK_LEAKED_CLASSLOADER, false);
 
-  private StreamExecutionEnvironment env;
-  private Table table;
+  private final StreamExecutionEnvironment env;
+  private final Table table;
 
   private Actions(StreamExecutionEnvironment env, Table table) {
     this.env = env;
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java
index 9876bb3861c4..670abebcb58a 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java
@@ -31,7 +31,7 @@
 
 public class RewriteDataFilesAction extends BaseRewriteDataFilesAction<RewriteDataFilesAction> {
 
-  private StreamExecutionEnvironment env;
+  private final StreamExecutionEnvironment env;
   private int maxParallelism;
 
   public RewriteDataFilesAction(StreamExecutionEnvironment env, Table table) {
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java
index 04e168385a36..f7e8e0c884cf 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java
@@ -55,7 +55,7 @@ public RowData map(GenericRecord genericRecord) throws Exception {
   public static AvroGenericRecordToRowDataMapper forAvroSchema(Schema avroSchema) {
     DataType dataType = AvroSchemaConverter.convertToDataType(avroSchema.toString());
     LogicalType logicalType = TypeConversions.fromDataToLogicalType(dataType);
-    RowType rowType = RowType.of(logicalType.getChildren().stream().toArray(LogicalType[]::new));
+    RowType rowType = RowType.of(logicalType.getChildren().toArray(new LogicalType[0]));
     return new AvroGenericRecordToRowDataMapper(rowType);
   }
 }
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java
index 0ffffd9cf49f..0b63e2721178 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java
@@ -39,7 +39,7 @@ class MapDataStatistics implements DataStatistics<MapDataStatistics, Map<SortKey
 
   @Override
   public boolean isEmpty() {
-    return statistics.size() == 0;
+    return statistics.isEmpty();
   }
 
   @Override
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java
index 8f95e3e554a0..8ef1f1fbb833 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java
@@ -64,7 +64,7 @@ public static RowDataToAvroGenericRecordConverter fromIcebergSchema(
   public static RowDataToAvroGenericRecordConverter fromAvroSchema(Schema avroSchema) {
     DataType dataType = AvroSchemaConverter.convertToDataType(avroSchema.toString());
     LogicalType logicalType = TypeConversions.fromDataToLogicalType(dataType);
-    RowType rowType = RowType.of(logicalType.getChildren().stream().toArray(LogicalType[]::new));
+    RowType rowType = RowType.of(logicalType.getChildren().toArray(new LogicalType[0]));
     return new RowDataToAvroGenericRecordConverter(rowType, avroSchema);
   }
 }
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java
index e9e3c159b07b..fef4ec45ed8a 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java
@@ -121,7 +121,7 @@ private ContinuousEnumerationResult discoverIncrementalSplits(
       LOG.info("Current table snapshot is already enumerated: {}", currentSnapshot.snapshotId());
       return new ContinuousEnumerationResult(Collections.emptyList(), lastPosition, lastPosition);
     } else {
-      Long lastConsumedSnapshotId = lastPosition != null ? lastPosition.snapshotId() : null;
+      Long lastConsumedSnapshotId = lastPosition.snapshotId();
       Snapshot toSnapshotInclusive =
           toSnapshotInclusive(
               lastConsumedSnapshotId, currentSnapshot, scanContext.maxPlanningSnapshotCount());
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java
index 024d0b101165..26fbad46c128 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java
@@ -29,7 +29,7 @@
 public class IcebergEnumeratorState implements Serializable {
   @Nullable private final IcebergEnumeratorPosition lastEnumeratedPosition;
   private final Collection<IcebergSourceSplitState> pendingSplits;
-  private int[] enumerationSplitCountHistory;
+  private final int[] enumerationSplitCountHistory;
 
   public IcebergEnumeratorState(Collection<IcebergSourceSplitState> pendingSplits) {
     this(null, pendingSplits);
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java
index 95d6db2cfbc4..f76f8a69ff0e 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java
@@ -174,10 +174,8 @@ private static Collection<IcebergSourceSplitState> deserializePendingSplits(
   private static void serializeEnumerationSplitCountHistory(
       DataOutputSerializer out, int[] enumerationSplitCountHistory) throws IOException {
     out.writeInt(enumerationSplitCountHistory.length);
-    if (enumerationSplitCountHistory.length > 0) {
-      for (int enumerationSplitCount : enumerationSplitCountHistory) {
-        out.writeInt(enumerationSplitCount);
-      }
+    for (int enumerationSplitCount : enumerationSplitCountHistory) {
+      out.writeInt(enumerationSplitCount);
     }
   }
 
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java
index a0395f29ac5b..841969666ee5 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java
@@ -129,7 +129,7 @@ public static String readLongUTF(DataInputDeserializer in) throws IOException {
           if (count > utflen) {
             throw new UTFDataFormatException("malformed input: partial character at end");
           }
-          char2 = (int) bytearr[count - 1];
+          char2 = bytearr[count - 1];
           if ((char2 & 0xC0) != 0x80) {
             throw new UTFDataFormatException("malformed input around byte " + count);
           }
@@ -141,8 +141,8 @@ public static String readLongUTF(DataInputDeserializer in) throws IOException {
           if (count > utflen) {
             throw new UTFDataFormatException("malformed input: partial character at end");
           }
-          char2 = (int) bytearr[count - 2];
-          char3 = (int) bytearr[count - 1];
+          char2 = bytearr[count - 2];
+          char3 = bytearr[count - 1];
           if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80)) {
             throw new UTFDataFormatException("malformed input around byte " + (count - 1));
           }
diff --git a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java
index 353cee56bebb..20b33e615e5f 100644
--- a/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java
+++ b/flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java
@@ -32,7 +32,7 @@ private FlinkPackage() {}
   /** Returns Flink version string like x.y.z */
   public static String version() {
     if (null == VERSION.get()) {
-      String detectedVersion = null;
+      String detectedVersion;
       try {
         detectedVersion = versionFromJar();
         // use unknown version in case exact implementation version can't be found from the jar
diff --git a/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java b/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java
index 0bb08e4f265a..e395414e925d 100644
--- a/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java
+++ b/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java
@@ -39,7 +39,7 @@
 
 public class TestFlinkCatalogTablePartitions extends CatalogTestBase {
 
-  private String tableName = "test_table";
+  private final String tableName = "test_table";
 
   @Parameter(index = 2)
   private FileFormat format;
diff --git a/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java b/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java
index 4ad302dde436..a7c58e551112 100644
--- a/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java
+++ b/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java
@@ -23,7 +23,7 @@
 import org.apache.iceberg.TestTables;
 
 public class TestTableLoader implements TableLoader {
-  private File dir;
+  private final File dir;
 
   public static TableLoader of(String dir) {
     return new TestTableLoader(dir);
diff --git a/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java b/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java
index 7033fd30e84f..187f2b0b9e31 100644
--- a/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java
+++ b/flink/v1.17/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java
@@ -122,7 +122,7 @@ public void testTimeUnit() throws IOException {
         new ColumnStatsWatermarkExtractor(SCHEMA, columnName, TimeUnit.MICROSECONDS);
 
     assertThat(extractor.extractWatermark(split(0)))
-        .isEqualTo(MIN_VALUES.get(0).get(columnName).longValue() / 1000L);
+        .isEqualTo(MIN_VALUES.get(0).get(columnName) / 1000L);
   }
 
   @TestTemplate
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java
index 06ac54617ae6..b96b47c5a785 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/Actions.java
@@ -30,8 +30,8 @@ public class Actions {
           // disable classloader check as Avro may cache class/object in the serializers.
           .set(CoreOptions.CHECK_LEAKED_CLASSLOADER, false);
 
-  private StreamExecutionEnvironment env;
-  private Table table;
+  private final StreamExecutionEnvironment env;
+  private final Table table;
 
   private Actions(StreamExecutionEnvironment env, Table table) {
     this.env = env;
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java
index 9876bb3861c4..670abebcb58a 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/actions/RewriteDataFilesAction.java
@@ -31,7 +31,7 @@
 
 public class RewriteDataFilesAction extends BaseRewriteDataFilesAction<RewriteDataFilesAction> {
 
-  private StreamExecutionEnvironment env;
+  private final StreamExecutionEnvironment env;
   private int maxParallelism;
 
   public RewriteDataFilesAction(StreamExecutionEnvironment env, Table table) {
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java
index 04e168385a36..f7e8e0c884cf 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/AvroGenericRecordToRowDataMapper.java
@@ -55,7 +55,7 @@ public RowData map(GenericRecord genericRecord) throws Exception {
   public static AvroGenericRecordToRowDataMapper forAvroSchema(Schema avroSchema) {
     DataType dataType = AvroSchemaConverter.convertToDataType(avroSchema.toString());
     LogicalType logicalType = TypeConversions.fromDataToLogicalType(dataType);
-    RowType rowType = RowType.of(logicalType.getChildren().stream().toArray(LogicalType[]::new));
+    RowType rowType = RowType.of(logicalType.getChildren().toArray(new LogicalType[0]));
     return new AvroGenericRecordToRowDataMapper(rowType);
   }
 }
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java
index 0ffffd9cf49f..0b63e2721178 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/sink/shuffle/MapDataStatistics.java
@@ -39,7 +39,7 @@ class MapDataStatistics implements DataStatistics<MapDataStatistics, Map<SortKey
 
   @Override
   public boolean isEmpty() {
-    return statistics.size() == 0;
+    return statistics.isEmpty();
   }
 
   @Override
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java
index 8f95e3e554a0..8ef1f1fbb833 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/RowDataToAvroGenericRecordConverter.java
@@ -64,7 +64,7 @@ public static RowDataToAvroGenericRecordConverter fromIcebergSchema(
   public static RowDataToAvroGenericRecordConverter fromAvroSchema(Schema avroSchema) {
     DataType dataType = AvroSchemaConverter.convertToDataType(avroSchema.toString());
     LogicalType logicalType = TypeConversions.fromDataToLogicalType(dataType);
-    RowType rowType = RowType.of(logicalType.getChildren().stream().toArray(LogicalType[]::new));
+    RowType rowType = RowType.of(logicalType.getChildren().toArray(new LogicalType[0]));
     return new RowDataToAvroGenericRecordConverter(rowType, avroSchema);
   }
 }
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java
index e9e3c159b07b..fef4ec45ed8a 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java
@@ -121,7 +121,7 @@ private ContinuousEnumerationResult discoverIncrementalSplits(
       LOG.info("Current table snapshot is already enumerated: {}", currentSnapshot.snapshotId());
       return new ContinuousEnumerationResult(Collections.emptyList(), lastPosition, lastPosition);
     } else {
-      Long lastConsumedSnapshotId = lastPosition != null ? lastPosition.snapshotId() : null;
+      Long lastConsumedSnapshotId = lastPosition.snapshotId();
       Snapshot toSnapshotInclusive =
           toSnapshotInclusive(
               lastConsumedSnapshotId, currentSnapshot, scanContext.maxPlanningSnapshotCount());
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java
index 024d0b101165..26fbad46c128 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorState.java
@@ -29,7 +29,7 @@
 public class IcebergEnumeratorState implements Serializable {
   @Nullable private final IcebergEnumeratorPosition lastEnumeratedPosition;
   private final Collection<IcebergSourceSplitState> pendingSplits;
-  private int[] enumerationSplitCountHistory;
+  private final int[] enumerationSplitCountHistory;
 
   public IcebergEnumeratorState(Collection<IcebergSourceSplitState> pendingSplits) {
     this(null, pendingSplits);
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java
index 95d6db2cfbc4..f76f8a69ff0e 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/IcebergEnumeratorStateSerializer.java
@@ -174,10 +174,8 @@ private static Collection<IcebergSourceSplitState> deserializePendingSplits(
   private static void serializeEnumerationSplitCountHistory(
       DataOutputSerializer out, int[] enumerationSplitCountHistory) throws IOException {
     out.writeInt(enumerationSplitCountHistory.length);
-    if (enumerationSplitCountHistory.length > 0) {
-      for (int enumerationSplitCount : enumerationSplitCountHistory) {
-        out.writeInt(enumerationSplitCount);
-      }
+    for (int enumerationSplitCount : enumerationSplitCountHistory) {
+      out.writeInt(enumerationSplitCount);
     }
   }
 
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java
index a0395f29ac5b..841969666ee5 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/split/SerializerHelper.java
@@ -129,7 +129,7 @@ public static String readLongUTF(DataInputDeserializer in) throws IOException {
           if (count > utflen) {
             throw new UTFDataFormatException("malformed input: partial character at end");
           }
-          char2 = (int) bytearr[count - 1];
+          char2 = bytearr[count - 1];
           if ((char2 & 0xC0) != 0x80) {
             throw new UTFDataFormatException("malformed input around byte " + count);
           }
@@ -141,8 +141,8 @@ public static String readLongUTF(DataInputDeserializer in) throws IOException {
           if (count > utflen) {
             throw new UTFDataFormatException("malformed input: partial character at end");
           }
-          char2 = (int) bytearr[count - 2];
-          char3 = (int) bytearr[count - 1];
+          char2 = bytearr[count - 2];
+          char3 = bytearr[count - 1];
           if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80)) {
             throw new UTFDataFormatException("malformed input around byte " + (count - 1));
           }
diff --git a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java
index 353cee56bebb..20b33e615e5f 100644
--- a/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java
+++ b/flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/util/FlinkPackage.java
@@ -32,7 +32,7 @@ private FlinkPackage() {}
   /** Returns Flink version string like x.y.z */
   public static String version() {
     if (null == VERSION.get()) {
-      String detectedVersion = null;
+      String detectedVersion;
       try {
         detectedVersion = versionFromJar();
         // use unknown version in case exact implementation version can't be found from the jar
diff --git a/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java b/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java
index 0bb08e4f265a..e395414e925d 100644
--- a/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java
+++ b/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestFlinkCatalogTablePartitions.java
@@ -39,7 +39,7 @@
 
 public class TestFlinkCatalogTablePartitions extends CatalogTestBase {
 
-  private String tableName = "test_table";
+  private final String tableName = "test_table";
 
   @Parameter(index = 2)
   private FileFormat format;
diff --git a/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java b/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java
index 4ad302dde436..a7c58e551112 100644
--- a/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java
+++ b/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/TestTableLoader.java
@@ -23,7 +23,7 @@
 import org.apache.iceberg.TestTables;
 
 public class TestTableLoader implements TableLoader {
-  private File dir;
+  private final File dir;
 
   public static TableLoader of(String dir) {
     return new TestTableLoader(dir);
diff --git a/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java b/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java
index 7033fd30e84f..187f2b0b9e31 100644
--- a/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java
+++ b/flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/source/reader/TestColumnStatsWatermarkExtractor.java
@@ -122,7 +122,7 @@ public void testTimeUnit() throws IOException {
         new ColumnStatsWatermarkExtractor(SCHEMA, columnName, TimeUnit.MICROSECONDS);
 
     assertThat(extractor.extractWatermark(split(0)))
-        .isEqualTo(MIN_VALUES.get(0).get(columnName).longValue() / 1000L);
+        .isEqualTo(MIN_VALUES.get(0).get(columnName) / 1000L);
   }
 
   @TestTemplate
diff --git a/spark/v3.3/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java b/spark/v3.3/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java
index 63d24f7da553..d8f9301a7d82 100644
--- a/spark/v3.3/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java
+++ b/spark/v3.3/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java
@@ -29,7 +29,7 @@
 
 class RandomGeneratingUDF implements Serializable {
   private final long uniqueValues;
-  private Random rand = new Random();
+  private final Random rand = new Random();
 
   RandomGeneratingUDF(long uniqueValues) {
     this.uniqueValues = uniqueValues;
@@ -43,8 +43,7 @@ UserDefinedFunction randomLongUDF() {
 
   UserDefinedFunction randomString() {
     return udf(
-            () -> (String) RandomUtil.generatePrimitive(Types.StringType.get(), rand),
-            DataTypes.StringType)
+            () -> RandomUtil.generatePrimitive(Types.StringType.get(), rand), DataTypes.StringType)
         .asNondeterministic()
         .asNonNullable();
   }
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java
index cdc0bf5f3cad..a4bcd0d8a5b5 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java
@@ -199,7 +199,7 @@ public Type map(Types.MapType map, Supplier<Type> keyResult, Supplier<Type> valu
         "Cannot project a map of optional values as required values: %s",
         map);
     Preconditions.checkArgument(
-        StringType.class.isInstance(requestedMap.keyType()),
+        requestedMap.keyType() instanceof StringType,
         "Invalid map key type (not string): %s",
         requestedMap.keyType());
 
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java
index 10b856a7acf0..f5d9a7af1c8f 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java
@@ -885,7 +885,7 @@ public static List<SparkPartition> getPartitions(
             JavaConverters.collectionAsScalaIterableConverter(ImmutableList.of(rootPath))
                 .asScala()
                 .toSeq(),
-            scala.collection.immutable.Map$.MODULE$.<String, String>empty(),
+            scala.collection.immutable.Map$.MODULE$.empty(),
             userSpecifiedSchema,
             fileStatusCache,
             Option.empty(),
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java
index 47690656b41d..af1e99df71d3 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java
@@ -182,7 +182,7 @@ public static List<SparkPartition> getPartitions(
       Option<scala.collection.immutable.Map<String, String>> scalaPartitionFilter;
       if (partitionFilter != null && !partitionFilter.isEmpty()) {
         Builder<Tuple2<String, String>, scala.collection.immutable.Map<String, String>> builder =
-            Map$.MODULE$.<String, String>newBuilder();
+            Map$.MODULE$.newBuilder();
         partitionFilter.forEach((key, value) -> builder.$plus$eq(Tuple2.apply(key, value)));
         scalaPartitionFilter = Option.apply(builder.result());
       } else {
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java
index b00ed42008f1..5fbb4117feb8 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java
@@ -116,7 +116,7 @@ public class DeleteOrphanFilesSparkAction extends BaseSparkAction<DeleteOrphanFi
   private Map<String, String> equalSchemes = flattenMap(EQUAL_SCHEMES_DEFAULT);
   private Map<String, String> equalAuthorities = Collections.emptyMap();
   private PrefixMismatchMode prefixMismatchMode = PrefixMismatchMode.ERROR;
-  private String location = null;
+  private String location;
   private long olderThanTimestamp = System.currentTimeMillis() - TimeUnit.DAYS.toMillis(3);
   private Dataset<Row> compareToFileList;
   private Consumer<String> deleteFunc = null;
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java
index ae547e206324..eed0b2b67b0a 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java
@@ -367,7 +367,7 @@ private Result doExecuteWithPartialProgress(
   Stream<RewriteFileGroup> toGroupStream(
       RewriteExecutionContext ctx, Map<StructLike, List<List<FileScanTask>>> groupsByPartition) {
     return groupsByPartition.entrySet().stream()
-        .filter(e -> e.getValue().size() != 0)
+        .filter(e -> !e.getValue().isEmpty())
         .flatMap(
             e -> {
               StructLike partition = e.getKey();
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java
index 78eb010b9b9c..62b7978f3800 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java
@@ -93,9 +93,9 @@ public class RewriteManifestsSparkAction
   private final long targetManifestSizeBytes;
   private final boolean shouldStageManifests;
 
-  private PartitionSpec spec = null;
+  private PartitionSpec spec;
   private Predicate<ManifestFile> predicate = manifest -> true;
-  private String outputLocation = null;
+  private String outputLocation;
 
   RewriteManifestsSparkAction(SparkSession spark, Table table) {
     super(spark);
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java
index ea1c52940175..8bc67c35c3d6 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java
@@ -309,7 +309,7 @@ private Result doExecuteWithPartialProgress(
     // stop commit service
     commitService.close();
     List<RewritePositionDeletesGroup> commitResults = commitService.results();
-    if (commitResults.size() == 0) {
+    if (commitResults.isEmpty()) {
       LOG.error(
           "{} is true but no rewrite commits succeeded. Check the logs to determine why the individual "
               + "commits failed. If this is persistent it may help to increase {} which will break the rewrite operation "
@@ -331,7 +331,7 @@ private Stream<RewritePositionDeletesGroup> toGroupStream(
       RewriteExecutionContext ctx,
       Map<StructLike, List<List<PositionDeletesScanTask>>> groupsByPartition) {
     return groupsByPartition.entrySet().stream()
-        .filter(e -> e.getValue().size() != 0)
+        .filter(e -> !e.getValue().isEmpty())
         .flatMap(
             e -> {
               StructLike partition = e.getKey();
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java
index 1a4f7052de39..e306bab32bcd 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java
@@ -561,7 +561,7 @@ private static class InternalRowWriter extends ParquetValueWriters.StructWriter<
 
     private InternalRowWriter(List<ParquetValueWriter<?>> writers, List<DataType> types) {
       super(writers);
-      this.types = types.toArray(new DataType[types.size()]);
+      this.types = types.toArray(new DataType[0]);
     }
 
     @Override
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java
index c24bcaad58b1..ef3138d677c6 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java
@@ -93,7 +93,7 @@ public class SparkScanBuilder
   private final SparkReadConf readConf;
   private final List<String> metaColumns = Lists.newArrayList();
 
-  private Schema schema = null;
+  private Schema schema;
   private boolean caseSensitive;
   private List<Expression> filterExpressions = null;
   private Filter[] pushedFilters = NO_FILTERS;
diff --git a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java
index 25393888f95c..c5c86c3ebf28 100644
--- a/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java
+++ b/spark/v3.3/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java
@@ -44,7 +44,7 @@ class SparkStagedScanBuilder implements ScanBuilder, SupportsPushDownRequiredCol
   private final SparkReadConf readConf;
   private final List<String> metaColumns = Lists.newArrayList();
 
-  private Schema schema = null;
+  private Schema schema;
 
   SparkStagedScanBuilder(SparkSession spark, Table table, CaseInsensitiveStringMap options) {
     this.spark = spark;
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java
index c96ed2909fe7..028d495b894d 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java
@@ -138,7 +138,7 @@ public static Object[][] parameters() {
 
   @Rule public TemporaryFolder temp = new TemporaryFolder();
 
-  private String baseTableName = "baseTable";
+  private final String baseTableName = "baseTable";
   private File tableDir;
   private String tableLocation;
   private final String type;
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java
index 478afcf09ae3..360b9ff20ec0 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java
@@ -67,7 +67,7 @@ public static List<Record> generateList(Schema schema, int numRecords, long seed
   public static Iterable<InternalRow> generateSpark(Schema schema, int numRecords, long seed) {
     return () ->
         new Iterator<InternalRow>() {
-          private SparkRandomDataGenerator generator = new SparkRandomDataGenerator(seed);
+          private final SparkRandomDataGenerator generator = new SparkRandomDataGenerator(seed);
           private int count = 0;
 
           @Override
@@ -114,7 +114,7 @@ private static Iterable<Record> newIterable(
     return () ->
         new Iterator<Record>() {
           private int count = 0;
-          private RandomDataGenerator generator = newGenerator.get();
+          private final RandomDataGenerator generator = newGenerator.get();
 
           @Override
           public boolean hasNext() {
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java
index 53a35eec61ce..2627ec0d2b55 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java
@@ -22,7 +22,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class LogMessage {
-  private static AtomicInteger idCounter = new AtomicInteger(0);
+  private static final AtomicInteger idCounter = new AtomicInteger(0);
 
   static LogMessage debug(String date, String message) {
     return new LogMessage(idCounter.getAndIncrement(), date, "DEBUG", message);
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java
index 3d94966eb76c..e5e0e350e50b 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java
@@ -87,7 +87,7 @@ public Integer next() {
   // Main reader class to test base class iteration logic.
   // Keeps track of iterator closure.
   private static class ClosureTrackingReader extends BaseReader<Integer, FileScanTask> {
-    private Map<String, CloseableIntegerRange> tracker = Maps.newHashMap();
+    private final Map<String, CloseableIntegerRange> tracker = Maps.newHashMap();
 
     ClosureTrackingReader(Table table, List<FileScanTask> tasks) {
       super(table, new BaseCombinedScanTask(tasks), null, null, false);
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java
index a5a3da39ad1f..693bcec9eb05 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java
@@ -92,7 +92,7 @@ public TestDataFrameWrites(String format) {
 
   private Map<String, String> tableProperties;
 
-  private org.apache.spark.sql.types.StructType sparkSchema =
+  private final org.apache.spark.sql.types.StructType sparkSchema =
       new org.apache.spark.sql.types.StructType(
           new org.apache.spark.sql.types.StructField[] {
             new org.apache.spark.sql.types.StructField(
@@ -107,16 +107,16 @@ public TestDataFrameWrites(String format) {
                 org.apache.spark.sql.types.Metadata.empty())
           });
 
-  private Schema icebergSchema =
+  private final Schema icebergSchema =
       new Schema(
           Types.NestedField.optional(1, "optionalField", Types.StringType.get()),
           Types.NestedField.required(2, "requiredField", Types.StringType.get()));
 
-  private List<String> data0 =
+  private final List<String> data0 =
       Arrays.asList(
           "{\"optionalField\": \"a1\", \"requiredField\": \"bid_001\"}",
           "{\"optionalField\": \"a2\", \"requiredField\": \"bid_002\"}");
-  private List<String> data1 =
+  private final List<String> data1 =
       Arrays.asList(
           "{\"optionalField\": \"d1\", \"requiredField\": \"bid_101\"}",
           "{\"optionalField\": \"d2\", \"requiredField\": \"bid_102\"}",
@@ -221,16 +221,15 @@ private void writeDataWithFailOnPartition(
     final int numPartitions = 10;
     final int partitionToFail = new Random().nextInt(numPartitions);
     MapPartitionsFunction<Row, Row> failOnFirstPartitionFunc =
-        (MapPartitionsFunction<Row, Row>)
-            input -> {
-              int partitionId = TaskContext.getPartitionId();
+        input -> {
+          int partitionId = TaskContext.getPartitionId();
 
-              if (partitionId == partitionToFail) {
-                throw new SparkException(
-                    String.format("Intended exception in partition %d !", partitionId));
-              }
-              return input;
-            };
+          if (partitionId == partitionToFail) {
+            throw new SparkException(
+                String.format("Intended exception in partition %d !", partitionId));
+          }
+          return input;
+        };
 
     Dataset<Row> df =
         createDataset(records, schema)
@@ -286,8 +285,8 @@ public void testNullableWithWriteOption() throws IOException {
         "Spark 3 rejects writing nulls to a required column", spark.version().startsWith("2"));
 
     File location = new File(temp.newFolder("parquet"), "test");
-    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location.toString());
-    String targetPath = String.format("%s/nullable_poc/targetFolder/", location.toString());
+    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location);
+    String targetPath = String.format("%s/nullable_poc/targetFolder/", location);
 
     tableProperties = ImmutableMap.of(TableProperties.WRITE_DATA_LOCATION, targetPath);
 
@@ -339,8 +338,8 @@ public void testNullableWithSparkSqlOption() throws IOException {
         "Spark 3 rejects writing nulls to a required column", spark.version().startsWith("2"));
 
     File location = new File(temp.newFolder("parquet"), "test");
-    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location.toString());
-    String targetPath = String.format("%s/nullable_poc/targetFolder/", location.toString());
+    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location);
+    String targetPath = String.format("%s/nullable_poc/targetFolder/", location);
 
     tableProperties = ImmutableMap.of(TableProperties.WRITE_DATA_LOCATION, targetPath);
 
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java
index 7313c18cc09d..6508b80e9c92 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java
@@ -92,7 +92,7 @@ public TestIdentityPartitionData(String format, boolean vectorized) {
 
   @Rule public TemporaryFolder temp = new TemporaryFolder();
 
-  private PartitionSpec spec =
+  private final PartitionSpec spec =
       PartitionSpec.builderFor(LOG_SCHEMA).identity("date").identity("level").build();
   private Table table = null;
   private Dataset<Row> logs = null;
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java
index 4ef022c50c59..86d709cf17ba 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java
@@ -163,7 +163,7 @@ private static Instant getInstant(String timestampWithoutZone) {
 
   @Rule public TemporaryFolder temp = new TemporaryFolder();
 
-  private PartitionSpec spec =
+  private final PartitionSpec spec =
       PartitionSpec.builderFor(LOG_SCHEMA)
           .identity("date")
           .identity("level")
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java
index bd20a628caa8..f420f1b955c0 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java
@@ -116,7 +116,7 @@ public void testStreamingWriteAppendMode() throws Exception {
       query.stop();
 
       // remove the last commit to force Spark to reprocess batch #1
-      File lastCommitFile = new File(checkpoint.toString() + "/commits/1");
+      File lastCommitFile = new File(checkpoint + "/commits/1");
       Assert.assertTrue("The commit file must be deleted", lastCommitFile.delete());
 
       // restart the query from the checkpoint
@@ -176,7 +176,7 @@ public void testStreamingWriteCompleteMode() throws Exception {
       query.stop();
 
       // remove the last commit to force Spark to reprocess batch #1
-      File lastCommitFile = new File(checkpoint.toString() + "/commits/1");
+      File lastCommitFile = new File(checkpoint + "/commits/1");
       Assert.assertTrue("The commit file must be deleted", lastCommitFile.delete());
 
       // restart the query from the checkpoint
@@ -236,7 +236,7 @@ public void testStreamingWriteCompleteModeWithProjection() throws Exception {
       query.stop();
 
       // remove the last commit to force Spark to reprocess batch #1
-      File lastCommitFile = new File(checkpoint.toString() + "/commits/1");
+      File lastCommitFile = new File(checkpoint + "/commits/1");
       Assert.assertTrue("The commit file must be deleted", lastCommitFile.delete());
 
       // restart the query from the checkpoint
diff --git a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java
index bf2200004282..36e887f49b55 100644
--- a/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java
+++ b/spark/v3.3/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java
@@ -278,7 +278,7 @@ public void testCreateTableLocation() throws Exception {
     File tableLocation = temp.newFolder();
     Assert.assertTrue(tableLocation.delete());
 
-    String location = "file:" + tableLocation.toString();
+    String location = "file:" + tableLocation;
 
     sql(
         "CREATE TABLE %s "
diff --git a/spark/v3.4/spark-extensions/src/test/java/org/apache/iceberg/spark/extensions/SparkRowLevelOperationsTestBase.java b/spark/v3.4/spark-extensions/src/test/java/org/apache/iceberg/spark/extensions/SparkRowLevelOperationsTestBase.java
index 5a1cc6343424..5b5dc1501335 100644
--- a/spark/v3.4/spark-extensions/src/test/java/org/apache/iceberg/spark/extensions/SparkRowLevelOperationsTestBase.java
+++ b/spark/v3.4/spark-extensions/src/test/java/org/apache/iceberg/spark/extensions/SparkRowLevelOperationsTestBase.java
@@ -262,7 +262,7 @@ protected <T> void createOrReplaceView(String name, List<T> data, Encoder<T> enc
   private Dataset<Row> toDS(String schema, String jsonData) {
     List<String> jsonRows =
         Arrays.stream(jsonData.split("\n"))
-            .filter(str -> str.trim().length() > 0)
+            .filter(str -> !str.trim().isEmpty())
             .collect(Collectors.toList());
     Dataset<String> jsonDS = spark.createDataset(jsonRows, Encoders.STRING());
 
diff --git a/spark/v3.4/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java b/spark/v3.4/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java
index 63d24f7da553..d8f9301a7d82 100644
--- a/spark/v3.4/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java
+++ b/spark/v3.4/spark/src/jmh/java/org/apache/iceberg/spark/action/RandomGeneratingUDF.java
@@ -29,7 +29,7 @@
 
 class RandomGeneratingUDF implements Serializable {
   private final long uniqueValues;
-  private Random rand = new Random();
+  private final Random rand = new Random();
 
   RandomGeneratingUDF(long uniqueValues) {
     this.uniqueValues = uniqueValues;
@@ -43,8 +43,7 @@ UserDefinedFunction randomLongUDF() {
 
   UserDefinedFunction randomString() {
     return udf(
-            () -> (String) RandomUtil.generatePrimitive(Types.StringType.get(), rand),
-            DataTypes.StringType)
+            () -> RandomUtil.generatePrimitive(Types.StringType.get(), rand), DataTypes.StringType)
         .asNondeterministic()
         .asNonNullable();
   }
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java
index bbbb46e803e2..f76f12355f1f 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/PruneColumnsWithReordering.java
@@ -203,7 +203,7 @@ public Type map(Types.MapType map, Supplier<Type> keyResult, Supplier<Type> valu
         "Cannot project a map of optional values as required values: %s",
         map);
     Preconditions.checkArgument(
-        StringType.class.isInstance(requestedMap.keyType()),
+        requestedMap.keyType() instanceof StringType,
         "Invalid map key type (not string): %s",
         requestedMap.keyType());
 
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java
index a81877c98b3d..cdf250b61b8f 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java
@@ -888,7 +888,7 @@ public static List<SparkPartition> getPartitions(
             JavaConverters.collectionAsScalaIterableConverter(ImmutableList.of(rootPath))
                 .asScala()
                 .toSeq(),
-            scala.collection.immutable.Map$.MODULE$.<String, String>empty(),
+            scala.collection.immutable.Map$.MODULE$.empty(),
             userSpecifiedSchema,
             fileStatusCache,
             Option.empty(),
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java
index 5af6b46b3178..6f57c7ae376c 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/SparkTableUtil.java
@@ -182,7 +182,7 @@ public static List<SparkPartition> getPartitions(
       Option<scala.collection.immutable.Map<String, String>> scalaPartitionFilter;
       if (partitionFilter != null && !partitionFilter.isEmpty()) {
         Builder<Tuple2<String, String>, scala.collection.immutable.Map<String, String>> builder =
-            Map$.MODULE$.<String, String>newBuilder();
+            Map$.MODULE$.newBuilder();
         partitionFilter.forEach((key, value) -> builder.$plus$eq(Tuple2.apply(key, value)));
         scalaPartitionFilter = Option.apply(builder.result());
       } else {
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java
index b00ed42008f1..5fbb4117feb8 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/DeleteOrphanFilesSparkAction.java
@@ -116,7 +116,7 @@ public class DeleteOrphanFilesSparkAction extends BaseSparkAction<DeleteOrphanFi
   private Map<String, String> equalSchemes = flattenMap(EQUAL_SCHEMES_DEFAULT);
   private Map<String, String> equalAuthorities = Collections.emptyMap();
   private PrefixMismatchMode prefixMismatchMode = PrefixMismatchMode.ERROR;
-  private String location = null;
+  private String location;
   private long olderThanTimestamp = System.currentTimeMillis() - TimeUnit.DAYS.toMillis(3);
   private Dataset<Row> compareToFileList;
   private Consumer<String> deleteFunc = null;
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java
index 7c516b96754a..a4c6642a3edf 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java
@@ -379,7 +379,7 @@ private Result doExecuteWithPartialProgress(
   Stream<RewriteFileGroup> toGroupStream(
       RewriteExecutionContext ctx, Map<StructLike, List<List<FileScanTask>>> groupsByPartition) {
     return groupsByPartition.entrySet().stream()
-        .filter(e -> e.getValue().size() != 0)
+        .filter(e -> !e.getValue().isEmpty())
         .flatMap(
             e -> {
               StructLike partition = e.getKey();
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java
index e9edfeb985c7..60e2b11881cb 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteManifestsSparkAction.java
@@ -103,9 +103,9 @@ public class RewriteManifestsSparkAction
   private final long targetManifestSizeBytes;
   private final boolean shouldStageManifests;
 
-  private PartitionSpec spec = null;
+  private PartitionSpec spec;
   private Predicate<ManifestFile> predicate = manifest -> true;
-  private String outputLocation = null;
+  private String outputLocation;
 
   RewriteManifestsSparkAction(SparkSession spark, Table table) {
     super(spark);
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java
index bdb0ee35273f..ccf874716db0 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/actions/RewritePositionDeleteFilesSparkAction.java
@@ -310,7 +310,7 @@ private Result doExecuteWithPartialProgress(
     // stop commit service
     commitService.close();
     List<RewritePositionDeletesGroup> commitResults = commitService.results();
-    if (commitResults.size() == 0) {
+    if (commitResults.isEmpty()) {
       LOG.error(
           "{} is true but no rewrite commits succeeded. Check the logs to determine why the individual "
               + "commits failed. If this is persistent it may help to increase {} which will break the rewrite operation "
@@ -332,7 +332,7 @@ private Stream<RewritePositionDeletesGroup> toGroupStream(
       RewriteExecutionContext ctx,
       Map<StructLike, List<List<PositionDeletesScanTask>>> groupsByPartition) {
     return groupsByPartition.entrySet().stream()
-        .filter(e -> e.getValue().size() != 0)
+        .filter(e -> !e.getValue().isEmpty())
         .flatMap(
             e -> {
               StructLike partition = e.getKey();
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java
index 1a4f7052de39..e306bab32bcd 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/SparkParquetWriters.java
@@ -561,7 +561,7 @@ private static class InternalRowWriter extends ParquetValueWriters.StructWriter<
 
     private InternalRowWriter(List<ParquetValueWriter<?>> writers, List<DataType> types) {
       super(writers);
-      this.types = types.toArray(new DataType[types.size()]);
+      this.types = types.toArray(new DataType[0]);
     }
 
     @Override
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkFileWriterFactory.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkFileWriterFactory.java
index 9b075b675565..50a1259c8626 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkFileWriterFactory.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkFileWriterFactory.java
@@ -48,7 +48,7 @@ class SparkFileWriterFactory extends BaseFileWriterFactory<InternalRow> {
   private StructType dataSparkType;
   private StructType equalityDeleteSparkType;
   private StructType positionDeleteSparkType;
-  private Map<String, String> writeProperties;
+  private final Map<String, String> writeProperties;
 
   SparkFileWriterFactory(
       Table table,
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java
index b430e6fca233..6b97e48133fd 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkScanBuilder.java
@@ -95,7 +95,7 @@ public class SparkScanBuilder
   private final List<String> metaColumns = Lists.newArrayList();
   private final InMemoryMetricsReporter metricsReporter;
 
-  private Schema schema = null;
+  private Schema schema;
   private boolean caseSensitive;
   private List<Expression> filterExpressions = null;
   private Predicate[] pushedPredicates = NO_PREDICATES;
diff --git a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java
index 25393888f95c..c5c86c3ebf28 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/source/SparkStagedScanBuilder.java
@@ -44,7 +44,7 @@ class SparkStagedScanBuilder implements ScanBuilder, SupportsPushDownRequiredCol
   private final SparkReadConf readConf;
   private final List<String> metaColumns = Lists.newArrayList();
 
-  private Schema schema = null;
+  private Schema schema;
 
   SparkStagedScanBuilder(SparkSession spark, Table table, CaseInsensitiveStringMap options) {
     this.spark = spark;
diff --git a/spark/v3.4/spark/src/main/java/org/apache/spark/sql/catalyst/analysis/NoSuchProcedureException.java b/spark/v3.4/spark/src/main/java/org/apache/spark/sql/catalyst/analysis/NoSuchProcedureException.java
index 2a89ac73e2c6..0cae0451905b 100644
--- a/spark/v3.4/spark/src/main/java/org/apache/spark/sql/catalyst/analysis/NoSuchProcedureException.java
+++ b/spark/v3.4/spark/src/main/java/org/apache/spark/sql/catalyst/analysis/NoSuchProcedureException.java
@@ -33,7 +33,7 @@ public NoSuchProcedureException(Identifier ident) {
         Option.empty(),
         Option.empty(),
         Option.empty(),
-        Map$.MODULE$.<String, String>empty(),
+        Map$.MODULE$.empty(),
         new QueryContext[0]);
   }
 }
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java
index c96ed2909fe7..028d495b894d 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/actions/TestCreateActions.java
@@ -138,7 +138,7 @@ public static Object[][] parameters() {
 
   @Rule public TemporaryFolder temp = new TemporaryFolder();
 
-  private String baseTableName = "baseTable";
+  private final String baseTableName = "baseTable";
   private File tableDir;
   private String tableLocation;
   private final String type;
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java
index 478afcf09ae3..360b9ff20ec0 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/data/RandomData.java
@@ -67,7 +67,7 @@ public static List<Record> generateList(Schema schema, int numRecords, long seed
   public static Iterable<InternalRow> generateSpark(Schema schema, int numRecords, long seed) {
     return () ->
         new Iterator<InternalRow>() {
-          private SparkRandomDataGenerator generator = new SparkRandomDataGenerator(seed);
+          private final SparkRandomDataGenerator generator = new SparkRandomDataGenerator(seed);
           private int count = 0;
 
           @Override
@@ -114,7 +114,7 @@ private static Iterable<Record> newIterable(
     return () ->
         new Iterator<Record>() {
           private int count = 0;
-          private RandomDataGenerator generator = newGenerator.get();
+          private final RandomDataGenerator generator = newGenerator.get();
 
           @Override
           public boolean hasNext() {
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java
index 53a35eec61ce..2627ec0d2b55 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/LogMessage.java
@@ -22,7 +22,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class LogMessage {
-  private static AtomicInteger idCounter = new AtomicInteger(0);
+  private static final AtomicInteger idCounter = new AtomicInteger(0);
 
   static LogMessage debug(String date, String message) {
     return new LogMessage(idCounter.getAndIncrement(), date, "DEBUG", message);
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java
index 3d94966eb76c..e5e0e350e50b 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestBaseReader.java
@@ -87,7 +87,7 @@ public Integer next() {
   // Main reader class to test base class iteration logic.
   // Keeps track of iterator closure.
   private static class ClosureTrackingReader extends BaseReader<Integer, FileScanTask> {
-    private Map<String, CloseableIntegerRange> tracker = Maps.newHashMap();
+    private final Map<String, CloseableIntegerRange> tracker = Maps.newHashMap();
 
     ClosureTrackingReader(Table table, List<FileScanTask> tasks) {
       super(table, new BaseCombinedScanTask(tasks), null, null, false);
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestCompressionSettings.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestCompressionSettings.java
index ea329f96d5b9..6b188cd1b120 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestCompressionSettings.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestCompressionSettings.java
@@ -215,7 +215,7 @@ private String getCompressionType(InputFile inputFile) throws Exception {
         return footer.getBlocks().get(0).getColumns().get(0).getCodec().name();
       default:
         FileContext fc = FileContext.getFileContext(CONF);
-        GenericDatumReader<Object> reader = new GenericDatumReader<Object>();
+        GenericDatumReader<Object> reader = new GenericDatumReader<>();
         DataFileReader fileReader =
             (DataFileReader)
                 DataFileReader.openReader(
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java
index a5a3da39ad1f..693bcec9eb05 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestDataFrameWrites.java
@@ -92,7 +92,7 @@ public TestDataFrameWrites(String format) {
 
   private Map<String, String> tableProperties;
 
-  private org.apache.spark.sql.types.StructType sparkSchema =
+  private final org.apache.spark.sql.types.StructType sparkSchema =
       new org.apache.spark.sql.types.StructType(
           new org.apache.spark.sql.types.StructField[] {
             new org.apache.spark.sql.types.StructField(
@@ -107,16 +107,16 @@ public TestDataFrameWrites(String format) {
                 org.apache.spark.sql.types.Metadata.empty())
           });
 
-  private Schema icebergSchema =
+  private final Schema icebergSchema =
       new Schema(
           Types.NestedField.optional(1, "optionalField", Types.StringType.get()),
           Types.NestedField.required(2, "requiredField", Types.StringType.get()));
 
-  private List<String> data0 =
+  private final List<String> data0 =
       Arrays.asList(
           "{\"optionalField\": \"a1\", \"requiredField\": \"bid_001\"}",
           "{\"optionalField\": \"a2\", \"requiredField\": \"bid_002\"}");
-  private List<String> data1 =
+  private final List<String> data1 =
       Arrays.asList(
           "{\"optionalField\": \"d1\", \"requiredField\": \"bid_101\"}",
           "{\"optionalField\": \"d2\", \"requiredField\": \"bid_102\"}",
@@ -221,16 +221,15 @@ private void writeDataWithFailOnPartition(
     final int numPartitions = 10;
     final int partitionToFail = new Random().nextInt(numPartitions);
     MapPartitionsFunction<Row, Row> failOnFirstPartitionFunc =
-        (MapPartitionsFunction<Row, Row>)
-            input -> {
-              int partitionId = TaskContext.getPartitionId();
+        input -> {
+          int partitionId = TaskContext.getPartitionId();
 
-              if (partitionId == partitionToFail) {
-                throw new SparkException(
-                    String.format("Intended exception in partition %d !", partitionId));
-              }
-              return input;
-            };
+          if (partitionId == partitionToFail) {
+            throw new SparkException(
+                String.format("Intended exception in partition %d !", partitionId));
+          }
+          return input;
+        };
 
     Dataset<Row> df =
         createDataset(records, schema)
@@ -286,8 +285,8 @@ public void testNullableWithWriteOption() throws IOException {
         "Spark 3 rejects writing nulls to a required column", spark.version().startsWith("2"));
 
     File location = new File(temp.newFolder("parquet"), "test");
-    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location.toString());
-    String targetPath = String.format("%s/nullable_poc/targetFolder/", location.toString());
+    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location);
+    String targetPath = String.format("%s/nullable_poc/targetFolder/", location);
 
     tableProperties = ImmutableMap.of(TableProperties.WRITE_DATA_LOCATION, targetPath);
 
@@ -339,8 +338,8 @@ public void testNullableWithSparkSqlOption() throws IOException {
         "Spark 3 rejects writing nulls to a required column", spark.version().startsWith("2"));
 
     File location = new File(temp.newFolder("parquet"), "test");
-    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location.toString());
-    String targetPath = String.format("%s/nullable_poc/targetFolder/", location.toString());
+    String sourcePath = String.format("%s/nullable_poc/sourceFolder/", location);
+    String targetPath = String.format("%s/nullable_poc/targetFolder/", location);
 
     tableProperties = ImmutableMap.of(TableProperties.WRITE_DATA_LOCATION, targetPath);
 
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java
index 45a523917f05..4ee77345dbe5 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestIdentityPartitionData.java
@@ -102,7 +102,7 @@ public TestIdentityPartitionData(String format, boolean vectorized, PlanningMode
 
   @Rule public TemporaryFolder temp = new TemporaryFolder();
 
-  private PartitionSpec spec =
+  private final PartitionSpec spec =
       PartitionSpec.builderFor(LOG_SCHEMA).identity("date").identity("level").build();
   private Table table = null;
   private Dataset<Row> logs = null;
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java
index c00549c68f3b..639d37c79336 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestPartitionPruning.java
@@ -169,7 +169,7 @@ private static Instant getInstant(String timestampWithoutZone) {
 
   @Rule public TemporaryFolder temp = new TemporaryFolder();
 
-  private PartitionSpec spec =
+  private final PartitionSpec spec =
       PartitionSpec.builderFor(LOG_SCHEMA)
           .identity("date")
           .identity("level")
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java
index bd20a628caa8..f420f1b955c0 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/source/TestStructuredStreaming.java
@@ -116,7 +116,7 @@ public void testStreamingWriteAppendMode() throws Exception {
       query.stop();
 
       // remove the last commit to force Spark to reprocess batch #1
-      File lastCommitFile = new File(checkpoint.toString() + "/commits/1");
+      File lastCommitFile = new File(checkpoint + "/commits/1");
       Assert.assertTrue("The commit file must be deleted", lastCommitFile.delete());
 
       // restart the query from the checkpoint
@@ -176,7 +176,7 @@ public void testStreamingWriteCompleteMode() throws Exception {
       query.stop();
 
       // remove the last commit to force Spark to reprocess batch #1
-      File lastCommitFile = new File(checkpoint.toString() + "/commits/1");
+      File lastCommitFile = new File(checkpoint + "/commits/1");
       Assert.assertTrue("The commit file must be deleted", lastCommitFile.delete());
 
       // restart the query from the checkpoint
@@ -236,7 +236,7 @@ public void testStreamingWriteCompleteModeWithProjection() throws Exception {
       query.stop();
 
       // remove the last commit to force Spark to reprocess batch #1
-      File lastCommitFile = new File(checkpoint.toString() + "/commits/1");
+      File lastCommitFile = new File(checkpoint + "/commits/1");
       Assert.assertTrue("The commit file must be deleted", lastCommitFile.delete());
 
       // restart the query from the checkpoint
diff --git a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java
index 4e34d662ffd1..927f6e21439f 100644
--- a/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java
+++ b/spark/v3.4/spark/src/test/java/org/apache/iceberg/spark/sql/TestCreateTable.java
@@ -277,7 +277,7 @@ public void testCreateTableLocation() throws Exception {
     File tableLocation = temp.newFolder();
     Assert.assertTrue(tableLocation.delete());
 
-    String location = "file:" + tableLocation.toString();
+    String location = "file:" + tableLocation;
 
     sql(
         "CREATE TABLE %s "