private StructObjectInspector genStructOI() {
    ArrayList<String> fieldNames1 = new ArrayList<String>();
    fieldNames1.add("theInt");
    fieldNames1.add("theBool");
    ArrayList<ObjectInspector> fieldObjectInspectors1 = new ArrayList<ObjectInspector>();
    fieldObjectInspectors1
        .add(PrimitiveObjectInspectorFactory.writableIntObjectInspector);
    fieldObjectInspectors1
        .add(PrimitiveObjectInspectorFactory.writableBooleanObjectInspector);
    return ObjectInspectorFactory
        .getStandardStructObjectInspector(fieldNames1, fieldObjectInspectors1);
  }
Unit tests for vector expression writers.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/expressions/TestVectorExpressionWriters.java