org.apache.hadoop.hive.ql.udf.generic
Class GenericUDFWhen

java.lang.Object
  extended by org.apache.hadoop.hive.ql.udf.generic.GenericUDF
      extended by org.apache.hadoop.hive.ql.udf.generic.GenericUDFWhen

public class GenericUDFWhen
extends GenericUDF

GenericUDF Class for SQL construct "CASE a WHEN b THEN c [ELSE f] END". NOTES: 1. a and b should have the same TypeInfo, or an exception will be thrown. 2. c and f should have the same TypeInfo, or an exception will be thrown.


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.hadoop.hive.ql.udf.generic.GenericUDF
GenericUDF.DeferredObject
 
Constructor Summary
GenericUDFWhen()
           
 
Method Summary
 Object evaluate(GenericUDF.DeferredObject[] arguments)
          Evaluate the GenericUDF with the arguments.
 String getDisplayString(String[] children)
          Get the String to be displayed in explain.
 ObjectInspector initialize(ObjectInspector[] arguments)
          Initialize this GenericUDF.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

GenericUDFWhen

public GenericUDFWhen()
Method Detail

initialize

public ObjectInspector initialize(ObjectInspector[] arguments)
                           throws UDFArgumentTypeException
Description copied from class: GenericUDF
Initialize this GenericUDF. This will be called once and only once per GenericUDF instance.

Specified by:
initialize in class GenericUDF
Parameters:
arguments - The ObjectInspector for the arguments
Returns:
The ObjectInspector for the return value
Throws:
UDFArgumentTypeException

evaluate

public Object evaluate(GenericUDF.DeferredObject[] arguments)
                throws HiveException
Description copied from class: GenericUDF
Evaluate the GenericUDF with the arguments.

Specified by:
evaluate in class GenericUDF
Parameters:
arguments - The arguments as DeferedObject, use DeferedObject.get() to get the actual argument Object. The Objects can be inspected by the ObjectInspectors passed in the initialize call.
Returns:
The
Throws:
HiveException

getDisplayString

public String getDisplayString(String[] children)
Description copied from class: GenericUDF
Get the String to be displayed in explain.

Specified by:
getDisplayString in class GenericUDF


Copyright © 2011 The Apache Software Foundation