GH-14890: [Java] Fix memory leak of DictionaryEncoder when exception thrown

java/vector/src/main/java/org/apache/arrow/vector/dictionary/DictionaryEncoder.java

@@ -94,12 +94,16 @@ public static ValueVector decode(ValueVector indices, Dictionary dictionary, Buf
     // copy the dictionary values into the decoded vector
     TransferPair transfer = dictionaryVector.getTransferPair(allocator);
     transfer.getTo().allocateNewSafe();
-
-    BaseIntVector baseIntVector = (BaseIntVector) indices;
-    retrieveIndexVector(baseIntVector, transfer, dictionaryCount, 0, count);
-    ValueVector decoded = transfer.getTo();
-    decoded.setValueCount(count);
-    return decoded;
+    try {
+      BaseIntVector baseIntVector = (BaseIntVector) indices;
+      retrieveIndexVector(baseIntVector, transfer, dictionaryCount, 0, count);
+      ValueVector decoded = transfer.getTo();
+      decoded.setValueCount(count);
+      return decoded;
+    } catch (Exception e) {
+      transfer.getTo().close();
+      throw e;
+    }
   }
 
   /**
@@ -192,10 +196,14 @@ public ValueVector encode(ValueVector vector) {
 
     BaseIntVector indices = (BaseIntVector) createdVector;
     indices.allocateNew();
-
-    buildIndexVector(vector, indices, hashTable, 0, vector.getValueCount());
-    indices.setValueCount(vector.getValueCount());
-    return indices;
+    try {
+      buildIndexVector(vector, indices, hashTable, 0, vector.getValueCount());
+      indices.setValueCount(vector.getValueCount());
+      return indices;
+    } catch (Exception e) {
+      indices.close();
+      throw e;
+    }
   }
 
   /**

java/vector/src/test/java/org/apache/arrow/vector/TestDictionaryVector.java

@@ -17,13 +17,9 @@
 
 package org.apache.arrow.vector;
 
-import static org.apache.arrow.vector.TestUtils.newVarBinaryVector;
-import static org.apache.arrow.vector.TestUtils.newVarCharVector;
+import static org.apache.arrow.vector.TestUtils.*;
 import static org.apache.arrow.vector.testing.ValueVectorDataPopulator.setVector;
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
@@ -881,6 +877,45 @@ public void testEncodeStructSubFieldWithCertainColumns() {
     }
   }
 
+  @Test
+  public void testNoMemoryLeak() {
+    // test no memory leak when encode
+    try (final VarCharVector vector = newVarCharVector("foo", allocator);
+         final VarCharVector dictionaryVector = newVarCharVector("dict", allocator)) {
+
+      setVector(vector, zero, one, two);
+      setVector(dictionaryVector, zero, one);
+
+      Dictionary dictionary =
+              new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
+
+      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
+        fail("There should be an exception when encoding");
+      } catch (Exception e) {
+        assertEquals("Dictionary encoding not defined for value:" + new Text(two), e.getMessage());
+      }
+    }
+    assertEquals("encode memory leak", 0, allocator.getAllocatedMemory());
+
+    // test no memory leak when decode
+    try (final IntVector indices = newVector(IntVector.class, "", Types.MinorType.INT, allocator);
+         final VarCharVector dictionaryVector = newVarCharVector("dict", allocator)) {
+
+      setVector(indices, 3);
+      setVector(dictionaryVector, zero, one);
+
+      Dictionary dictionary =
+              new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
+
+      try (final ValueVector decoded = DictionaryEncoder.decode(indices, dictionary, allocator)) {
+        fail("There should be an exception when decoding");
+      } catch (Exception e) {
+        assertEquals("Provided dictionary does not contain value for index 3", e.getMessage());
+      }
+    }
+    assertEquals("decode memory leak", 0, allocator.getAllocatedMemory());
+  }
+
   private void testDictionary(Dictionary dictionary, ToIntBiFunction<ValueVector, Integer> valGetter) {
     try (VarCharVector vector = new VarCharVector("vector", allocator)) {
       setVector(vector, "1", "3", "5", "7", "9");