How to use

addVector

method

in

org.apache.arrow.vector.complex.UnionVector

public void materialize(Field field) {
 for (Field child : field.getChildren()) {
  FieldVector v = TypeHelper.getNewVector(child, unionVector.getAllocator());
  ComplexTypeHelper.materialize(v, child);
  unionVector.addVector(v);
 }
}

private FieldWriter promoteToUnion() {
 String name = vector.getField().getName();
 TransferPair tp = vector.getTransferPair(vector.getMinorType().name().toLowerCase(), vector.getAllocator());
 tp.transfer();
 if (parentContainer != null) {
  // TODO allow dictionaries in complex types
  unionVector = parentContainer.addOrGetUnion(name);
  unionVector.allocateNew();
 } else if (listVector != null) {
  unionVector = listVector.promoteToUnion();
 }
 unionVector.addVector((FieldVector) tp.getTo());
 writer = new UnionWriter(unionVector, nullableStructWriterFactory);
 writer.setPosition(idx());
 for (int i = 0; i <= idx(); i++) {
  unionVector.setType(i, vector.getMinorType());
 }
 vector = null;
 state = State.UNION;
 return writer;
}