From bbfb7b964fd6e0a0675b444cf50a96e41177c314 Mon Sep 17 00:00:00 2001
From: James Henderson <james@jarohen.dev>
Date: Fri, 19 Jul 2024 02:52:34 +0100
Subject: [PATCH] GH-43320: [Java] fix for SchemaChangeRuntimeException
 transferring empty FixedSizeListVector (#43321)

### What changes are included in this PR?

When we create a FSLV through TransferImpl, we check to see if the source's element vector is a ZeroVector and, if not, we don't call addOrGetVector.

### Are these changes tested?

Yep - see TestFixedSizeListVector

### Are there any user-facing changes?

No
* GitHub Issue: #43320

Authored-by: James Henderson <james@jarohen.dev>
Signed-off-by: David Li <li.davidm96@gmail.com>
---
 .../vector/complex/FixedSizeListVector.java   |  4 ++-
 .../arrow/vector/TestFixedSizeListVector.java | 29 +++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/java/vector/src/main/java/org/apache/arrow/vector/complex/FixedSizeListVector.java b/java/vector/src/main/java/org/apache/arrow/vector/complex/FixedSizeListVector.java
index 7a88eaf162314..cb4550848088c 100644
--- a/java/vector/src/main/java/org/apache/arrow/vector/complex/FixedSizeListVector.java
+++ b/java/vector/src/main/java/org/apache/arrow/vector/complex/FixedSizeListVector.java
@@ -602,7 +602,9 @@ public TransferImpl(Field field, BufferAllocator allocator, CallBack callBack) {
 
     public TransferImpl(FixedSizeListVector to) {
       this.to = to;
-      to.addOrGetVector(vector.getField().getFieldType());
+      if (!(vector instanceof ZeroVector)) {
+        to.addOrGetVector(vector.getField().getFieldType());
+      }
       dataPair = vector.makeTransferPair(to.vector);
     }
 
diff --git a/java/vector/src/test/java/org/apache/arrow/vector/TestFixedSizeListVector.java b/java/vector/src/test/java/org/apache/arrow/vector/TestFixedSizeListVector.java
index fc220e0f05a14..f582406de6808 100644
--- a/java/vector/src/test/java/org/apache/arrow/vector/TestFixedSizeListVector.java
+++ b/java/vector/src/test/java/org/apache/arrow/vector/TestFixedSizeListVector.java
@@ -26,6 +26,7 @@
 import java.math.BigDecimal;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import org.apache.arrow.memory.BufferAllocator;
@@ -243,6 +244,34 @@ public void testTransferPair() {
     }
   }
 
+  @Test
+  public void testTransferEmptyVector() throws Exception {
+    // #43320
+    try (FixedSizeListVector src =
+            new FixedSizeListVector(
+                "src", allocator, FieldType.nullable(new ArrowType.FixedSizeList(2)), null);
+        FixedSizeListVector dest =
+            new FixedSizeListVector(
+                "dest", allocator, FieldType.nullable(new ArrowType.FixedSizeList(2)), null)) {
+      src.makeTransferPair(dest).transfer();
+
+      IntVector els =
+          (IntVector) dest.addOrGetVector(FieldType.nullable(MinorType.INT.getType())).getVector();
+
+      dest.allocateNew();
+      dest.startNewValue(0);
+      els.setSafe(0, 1);
+      els.setSafe(1, 2);
+      dest.setValueCount(1);
+
+      List<Integer> expected = new ArrayList<>(2);
+      expected.add(1);
+      expected.add(2);
+
+      assertEquals(expected, dest.getObject(0));
+    }
+  }
+
   @Test
   public void testConsistentChildName() throws Exception {
     try (FixedSizeListVector listVector =