[GitHub] [arrow] lfygh opened a new issue, #35111: Should ListVector.reset() reset the position(index)?

["lfygh (via GitHub)" <gi...@apache.org>]

lfygh opened a new issue, #35111:
URL: https://github.com/apache/arrow/issues/35111

   ### Describe the bug, including details regarding any error messages, version, and platform.
   
   
   ```java
   RootAllocator rootAllocator = new RootAllocator();
           ListVector identity = ListVector.empty("identity", rootAllocator);
           VectorSchemaRoot root = new VectorSchemaRoot(List.of(identity));
           root.allocateNew();
   
           UnionListWriter writer = identity.getWriter();
   
           byte[] bytes1 = "hello1".getBytes(StandardCharsets.UTF_8);
           ArrowBuf buffer = rootAllocator.buffer(bytes1.length);
           buffer.setBytes(0,bytes1);
           writer.startList();
           writer.varChar().writeVarChar(0,bytes1.length,buffer);
           writer.endList();
           root.setRowCount(1);
           System.out.println(root.contentToTSVString());
           
           root.getFieldVectors().forEach(ValueVector::reset);   //reset fieldVector
   
           byte[] bytes3 = "hello2".getBytes(StandardCharsets.UTF_8);
           buffer.setBytes(0,bytes3);
           writer.startList();
           writer.varChar().writeVarChar(0,bytes3.length,buffer);
           writer.endList();
   
           root.setRowCount(1);
           System.out.println(root.contentToTSVString());
   ```
   
   the result is
   ```
   identity
   ["hello1"]
   
   identity
   null
   ```
   
   The above results are confusing。 
   
   The correct way is using the `writer.setPosition(index)`,
   
   I don't know if it's a bug or other something.
   
   ### Component(s)
   
   Java


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