cascading.operation.aggregator
Class MinValue

java.lang.Object
  cascading.operation.BaseOperation<ExtremaValueBase.Context>
      cascading.operation.aggregator.ExtremaValueBase
          cascading.operation.aggregator.MinValue

All Implemented Interfaces:

DeclaresResults, Aggregator<ExtremaValueBase.Context>, Operation<ExtremaValueBase.Context>, Serializable

public class MinValue
extends ExtremaValueBase

Class Min is an Aggregator that returns the minimum value encountered in the current group.

As opposed to the Min class, values are expected to be Comparable types vs numeric representations and the Comparable.compareTo(Object) result is use for min comparison.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class cascading.operation.aggregator.ExtremaValueBase

ExtremaValueBase.Context

Field Summary

static String

FIELD_NAME Field FIELD_NAME

Fields inherited from class cascading.operation.aggregator.ExtremaValueBase

ignoreValues

Fields inherited from class cascading.operation.BaseOperation

fieldDeclaration, numArgs, trace

Fields inherited from interface cascading.operation.Operation

ANY

Constructor Summary

MinValue()
Constructs a new instance that returns the Min value encountered in the field name "min".

MinValue(Fields fieldDeclaration)
Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.

MinValue(Fields fieldDeclaration, Object... ignoreValues)
Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.

Method Summary

protected boolean

compare(Comparable lhs, Comparable rhs) Allows subclasses to provide own comparison method.

Methods inherited from class cascading.operation.aggregator.ExtremaValueBase

aggregate, complete, equals, getIgnoreValues, getResult, hashCode, prepare, start

Methods inherited from class cascading.operation.BaseOperation

cleanup, flush, getFieldDeclaration, getNumArgs, getTrace, isSafe, printOperationInternal, toString, toStringInternal

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface cascading.operation.Operation

cleanup, flush, getFieldDeclaration, getNumArgs, isSafe

Field Detail

FIELD_NAME

public static final String FIELD_NAME

Field FIELD_NAME

See Also:

Constant Field Values

Constructor Detail

MinValue

public MinValue()

Constructs a new instance that returns the Min value encountered in the field name "min".

MinValue

@ConstructorProperties(value="fieldDeclaration")
public MinValue(Fields fieldDeclaration)

Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.

Parameters:

fieldDeclaration - of type Fields

MinValue

@ConstructorProperties(value={"fieldDeclaration","ignoreValues"})
public MinValue(Fields fieldDeclaration,
                                           Object... ignoreValues)

Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name. Any argument matching an ignoredValue won't be compared.

Parameters:

fieldDeclaration - of type Fields

ignoreValues - of type Object...

Method Detail

compare

protected boolean compare(Comparable lhs,
                          Comparable rhs)

Description copied from class: ExtremaValueBase

Allows subclasses to provide own comparison method.

Specified by:

compare in class ExtremaValueBase

Parameters:

lhs - Comparable type

rhs - Comparable type

Returns:

true if the rhs should be retained as the result value