org.apache.commons.collections4.comparators

Class TransformingComparator<I,O>

java.lang.Object

org.apache.commons.collections4.comparators.TransformingComparator<I,O>

Type Parameters:

I - the input type to the transformer

O - the output type from the transformer

All Implemented Interfaces:

Serializable, Comparator<I>

public class TransformingComparator<I,O>
extends Object
implements Comparator<I>, Serializable

Decorates another Comparator with transformation behavior. That is, the return value from the transform operation will be passed to the decorated compare method.

This class is Serializable from Commons Collections 4.0.

Since:

2.1

See Also:

Transformer, ComparableComparator, Serialized Form

Constructor Summary

Constructors

Constructor and Description
TransformingComparator(Transformer<? super I,? extends O> transformer) Constructs an instance with the given Transformer and a ComparableComparator.
TransformingComparator(Transformer<? super I,? extends O> transformer, Comparator<O> decorated) Constructs an instance with the given Transformer and Comparator.

Method Summary

Modifier and Type	Method and Description
int	compare(I obj1, I obj2) Returns the result of comparing the values from the transform operation.
boolean	equals(Object object) Returns true iff that Object is is a Comparator whose ordering is known to be equivalent to mine.
int	hashCode() Implement a hash code for this comparator that is consistent with equals.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Detail

TransformingComparator

public TransformingComparator(Transformer<? super I,? extends O> transformer)

Constructs an instance with the given Transformer and a ComparableComparator.

Parameters:

transformer - what will transform the arguments to compare

TransformingComparator

public TransformingComparator(Transformer<? super I,? extends O> transformer,
                              Comparator<O> decorated)

Constructs an instance with the given Transformer and Comparator.

Parameters:

transformer - what will transform the arguments to compare

decorated - the decorated Comparator

Method Detail

compare

public int compare(I obj1,
                   I obj2)

Returns the result of comparing the values from the transform operation.

Specified by:

compare in interface Comparator<I>

Parameters:

obj1 - the first object to transform then compare

obj2 - the second object to transform then compare

Returns:

negative if obj1 is less, positive if greater, zero if equal

hashCode

public int hashCode()

Implement a hash code for this comparator that is consistent with equals.

Overrides:

hashCode in class Object

Returns:

a hash code for this comparator.

equals

public boolean equals(Object object)

Returns true iff that Object is is a Comparator whose ordering is known to be equivalent to mine.

This implementation returns true iff that is a TransformingComparator whose attributes are equal to mine.

Specified by:

equals in interface Comparator<I>

Overrides:

equals in class Object

Parameters:

object - the object to compare to

Returns:

true if equal