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<document>

  <properties>
    <title>Hadoop Hive- Reflect User Defined Function</title>
    <author email="hive-user@hadoop.apache.org">Hadoop Hive Documentation Team</author>
  </properties>

  <body>
<section name="Reflect (Generic) UDF" href="reflect">

<p>A java class and method often exists to handle the exact function a user would like to use in hive. Rather
then having to write a wrapper UDF to call this method, the majority of these methods can be called using reflect udf. Reflect uses 
java reflection to instantiate and call methods of objects, it can also call static functions. The method must return a primative type
or a type that hive knows how to serialize.
</p>

<source><![CDATA[SELECT reflect("java.lang.String", "valueOf", 1),
       reflect("java.lang.String", "isEmpty"),
       reflect("java.lang.Math", "max", 2, 3),
       reflect("java.lang.Math", "min", 2, 3),
       reflect("java.lang.Math", "round", 2.5),
       reflect("java.lang.Math", "exp", 1.0),
       reflect("java.lang.Math", "floor", 1.9)
FROM src LIMIT 1;


1	true	3	2	3	2.7182818284590455	1.0]]></source>

</section>
</body>
</document>
