GH-469: Unify ValueVector.getObject and VariableWidthFieldVector.get behavior about null value (#486)

Fixes #469.

Author: aqni

vector/src/main/java/org/apache/arrow/vector/FixedSizeBinaryVector.java

@@ -149,7 +149,10 @@ public void get(int index, NullableFixedSizeBinaryHolder holder) {
    */
   @Override
   public byte[] getObject(int index) {
-    return get(index);
+    if (isSet(index) == 0) {
+      return null;
+    }
+    return get(valueBuffer, index, byteWidth);
   }
 
   public int getByteWidth() {

vector/src/main/java/org/apache/arrow/vector/LargeVarBinaryVector.java

@@ -16,6 +16,8 @@
  */
 package org.apache.arrow.vector;
 
+import static org.apache.arrow.vector.NullCheckingForGet.NULL_CHECKING_ENABLED;
+
 import org.apache.arrow.memory.BufferAllocator;
 import org.apache.arrow.memory.ReusableBuffer;
 import org.apache.arrow.vector.complex.impl.LargeVarBinaryReaderImpl;
@@ -95,7 +97,7 @@ public MinorType getMinorType() {
    */
   public byte[] get(int index) {
     assert index >= 0;
-    if (isSet(index) == 0) {
+    if (NULL_CHECKING_ENABLED && isSet(index) == 0) {
       return null;
     }
     final long startOffset = getStartOffset(index);
@@ -127,7 +129,14 @@ public void read(int index, ReusableBuffer<?> buffer) {
    */
   @Override
   public byte[] getObject(int index) {
-    return get(index);
+    if (isSet(index) == 0) {
+      return null;
+    }
+    final long startOffset = getStartOffset(index);
+    final long dataLength = getEndOffset(index) - startOffset;
+    final byte[] result = new byte[(int) dataLength];
+    valueBuffer.getBytes(startOffset, result, 0, (int) dataLength);
+    return result;
   }
 
   /**

vector/src/main/java/org/apache/arrow/vector/LargeVarCharVector.java

@@ -101,7 +101,7 @@ public Types.MinorType getMinorType() {
   @Override
   public byte[] get(int index) {
     assert index >= 0;
-    if (isSet(index) == 0) {
+    if (NULL_CHECKING_ENABLED && isSet(index) == 0) {
       return null;
     }
     final long startOffset = getStartOffset(index);
@@ -120,7 +120,7 @@ public byte[] get(int index) {
   @Override
   public Text getObject(int index) {
     assert index >= 0;
-    if (NULL_CHECKING_ENABLED && isSet(index) == 0) {
+    if (isSet(index) == 0) {
       return null;
     }
 

vector/src/main/java/org/apache/arrow/vector/ValueVector.java

@@ -264,7 +264,7 @@ public interface ValueVector extends Closeable, Iterable<ValueVector> {
    * Get friendly type object from the vector.
    *
    * @param index index of object to get
-   * @return friendly type object
+   * @return friendly type object, null if value is unset
    */
   Object getObject(int index);
 

vector/src/main/java/org/apache/arrow/vector/VarBinaryVector.java

@@ -128,7 +128,15 @@ public void read(int index, ReusableBuffer<?> buffer) {
    */
   @Override
   public byte[] getObject(int index) {
-    return get(index);
+    if (isSet(index) == 0) {
+      return null;
+    }
+
+    final int startOffset = getStartOffset(index);
+    final int dataLength = getEndOffset(index) - startOffset;
+    final byte[] result = new byte[dataLength];
+    valueBuffer.getBytes(startOffset, result, 0, dataLength);
+    return result;
   }
 
   /**

vector/src/main/java/org/apache/arrow/vector/VarCharVector.java

@@ -117,7 +117,7 @@ public byte[] get(int index) {
   @Override
   public Text getObject(int index) {
     assert index >= 0;
-    if (NULL_CHECKING_ENABLED && isSet(index) == 0) {
+    if (isSet(index) == 0) {
       return null;
     }
 

vector/src/main/java/org/apache/arrow/vector/ViewVarBinaryVector.java

@@ -122,7 +122,10 @@ public void read(int index, ReusableBuffer<?> buffer) {
    */
   @Override
   public byte[] getObject(int index) {
-    return get(index);
+    if (isSet(index) == 0) {
+      return null;
+    }
+    return getData(index);
   }
 
   /**

vector/src/main/java/org/apache/arrow/vector/ViewVarCharVector.java

@@ -115,7 +115,7 @@ public byte[] get(int index) {
   @Override
   public Text getObject(int index) {
     assert index >= 0;
-    if (NULL_CHECKING_ENABLED && isSet(index) == 0) {
+    if (isSet(index) == 0) {
       return null;
     }