[I] [Java] Does arrow allow map as map value (nested map) ? [arrow]

[via GitHub]

0xderek opened a new issue, #44353:
URL: https://github.com/apache/arrow/issues/44353

   ### Describe the usage question you have. Please include as many useful 
details as  possible.
   
   
   I'm trying to build a MapVector with map as its value, for example Map<Int, 
Map<Int, Int>>, but the code throws exception when writing data into the inner 
map.
   
   ```java
       @Test
       void testMapOfMap() {
           MapVector vector = new MapVector("map", allocator,
                   FieldType.nullable(new ArrowType.Map(false)), null);
           MapWriter writer = vector.getWriter();
   
           writer.startMap();
           writer.startEntry();
   
           writer.key().integer().writeInt(1);
   
           MapWriter innerMapWriter = writer.value().map();
           innerMapWriter.startMap();                         // <- throws at 
this line
           innerMapWriter.startEntry();
           innerMapWriter.key().integer().writeInt(1);
           innerMapWriter.value().integer().writeInt(2);
           innerMapWriter.endEntry();
           innerMapWriter.endMap();
   
           writer.endEntry();
           writer.endMap();
   
           vector.setValueCount(1);
           log.info(vector.toString());
       }
   ```
   
   Does Arrow support this? Or am I using this wrong?
   
   BTW I'm using JDK 8 and Arrow 17.0.0.
   
   Thanks
   
   ### Component(s)
   
   Java


-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: issues-unsubscr...@arrow.apache.org.apache.org

For queries about this service, please contact Infrastructure at:
us...@infra.apache.org