org.apache.hadoop.mapred.lib.aggregate

Class UserDefinedValueAggregatorDescriptor

java.lang.Object

org.apache.hadoop.mapreduce.lib.aggregate.UserDefinedValueAggregatorDescriptor

org.apache.hadoop.mapred.lib.aggregate.UserDefinedValueAggregatorDescriptor

All Implemented Interfaces:

ValueAggregatorDescriptor

@InterfaceAudience.Public
@InterfaceStability.Stable
public class UserDefinedValueAggregatorDescriptor
extends UserDefinedValueAggregatorDescriptor
implements ValueAggregatorDescriptor

This class implements a wrapper for a user defined value aggregator descriptor. It serves two functions: One is to create an object of ValueAggregatorDescriptor from the name of a user defined class that may be dynamically loaded. The other is to delegate invocations of generateKeyValPairs function to the created object.

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.lib.aggregate.UserDefinedValueAggregatorDescriptor

theAggregatorDescriptor

Fields inherited from interface org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorDescriptor

ONE, TYPE_SEPARATOR

Constructor Summary

Constructors

Constructor and Description
UserDefinedValueAggregatorDescriptor(String className, JobConf job)

Method Summary

Methods

Modifier and Type	Method and Description
void	configure(JobConf job) Do nothing.
static Object	createInstance(String className) Create an instance of the given class

Methods inherited from class org.apache.hadoop.mapreduce.lib.aggregate.UserDefinedValueAggregatorDescriptor

configure, generateKeyValPairs, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.hadoop.mapreduce.lib.aggregate.ValueAggregatorDescriptor

configure, generateKeyValPairs

Constructor Detail

UserDefinedValueAggregatorDescriptor

public UserDefinedValueAggregatorDescriptor(String className,
                                    JobConf job)

Parameters:

className - the class name of the user defined descriptor class

job - a configure object used for decriptor configuration

Method Detail

createInstance

public static Object createInstance(String className)

Create an instance of the given class

Parameters:

className - the name of the class

Returns:

a dynamically created instance of the given class

configure

public void configure(JobConf job)

Do nothing.

Parameters:

job - a JobConf object that may contain the information that can be used to configure the object.