@Override
  public ObjectInspector initialize(ObjectInspector[] arg0) throws UDFArgumentException {
    converters = new ObjectInspectorConverters.Converter[arg0.length];
    for (int i = 0; i < arg0.length; i++) {
      converters[i] = ObjectInspectorConverters.getConverter(arg0[i],
              PrimitiveObjectInspectorFactory.writableStringObjectInspector);
    }

    // evaluate will return a Text object
    return PrimitiveObjectInspectorFactory.writableStringObjectInspector;
  }
UDF to obfuscate input data appending "Hello "
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/UDFHelloTest.java