Apache Commons Collections 4.4 · org.apache.commons.collections4.comparators.ComparableComparator

A Comparator that compares Comparable objects.

This Comparator is useful, for example, for enforcing the natural order in custom implementations of SortedSet and SortedMap.

Note

In the 2.0 and 2.1 releases of Commons Collections, this class would throw a ClassCastException if either of the arguments to compare were null, not Comparable, or for which compareTo gave inconsistent results. This is no longer the case. See compare for details.

Field Summary

Modifier and Type	Field and Description
public static final ComparableComparator<E extends Comparable<? super E>>	INSTANCE The singleton instance.
private static final long	serialVersionUID Serialization version.

Constructor Summary

Access	Constructor and Description
public	ComparableComparator() Constructor whose use should be avoided.

Method Summary

Modifier and Type	Method and Description
public static < the element type E extends Comparable<? super E>> ComparableComparator<E>	Returns: the singleton ComparableComparator comparableComparator() Gets the singleton instance of a ComparableComparator.
public int	Returns: negative if obj1 is less, positive if greater, zero if equal compare(final E the first object to compare obj1, final E the second object to compare obj2) Implements java.util.Comparator.compare. Compare the two `Comparable` arguments.
public boolean	Returns: `true` if equal equals(final Object the object to compare with object) Overrides java.lang.Object.equals. Implements java.util.Comparator.equals. Returns `true` iff that Object is is a `Comparator` whose ordering is known to be equivalent to mine.
public int	Returns: a hash code for this comparator. hashCode() Overrides java.lang.Object.hashCode. Implement a hash code for this comparator that is consistent with `equals`.

Inherited from java.lang.Object:: clone finalize getClass notify notifyAll toString wait wait wait

Field Detail

INSTANCE	back to summary
public static final ComparableComparator<E extends Comparable<? super E>> INSTANCE The singleton instance. Annotations @SuppressWarnings:rawtypes

serialVersionUID	back to summary
private static final long serialVersionUID Serialization version.

Constructor Detail

ComparableComparator back to summary

ComparableComparator	back to summary
public ComparableComparator() Constructor whose use should be avoided. Please use the `comparableComparator()` method whenever possible.

public ComparableComparator()

Constructor whose use should be avoided.

Please use the comparableComparator() method whenever possible.

Method Detail

comparableComparator	back to summary
public static <E extends Comparable<? super E>> ComparableComparator<E> comparableComparator() Gets the singleton instance of a ComparableComparator. Developers are encouraged to use the comparator returned from this method instead of constructing a new instance to reduce allocation and GC overhead when multiple comparable comparators may be used in the same VM. Parameters <E> the element type Returns:ComparableComparator<E> the singleton ComparableComparator Since 4.0

comparableComparator

back to summary

public static <E extends Comparable<? super E>> ComparableComparator<E> comparableComparator()

Gets the singleton instance of a ComparableComparator.

Developers are encouraged to use the comparator returned from this method instead of constructing a new instance to reduce allocation and GC overhead when multiple comparable comparators may be used in the same VM.

Parameters

<E>: the element type

Returns:ComparableComparator<E>

the singleton ComparableComparator

Since

4.0

compare back to summary

compare	back to summary
public int compare(final E obj1, final E obj2) Implements java.util.Comparator.compare. Compare the two `Comparable` arguments. This method is equivalent to: ((Comparable)obj1).compareTo(obj2) Parameters obj1:E the first object to compare obj2:E the second object to compare Returns:int negative if obj1 is less, positive if greater, zero if equal Annotations @Override Exceptions NullPointerException: if obj1 is `null`, or when `((Comparable)obj1).compareTo(obj2)` does ClassCastException: if obj1 is not a `Comparable`, or when `((Comparable)obj1).compareTo(obj2)` does

public int compare(final E obj1, final E obj2)

Implements java.util.Comparator.compare.

Compare the two Comparable arguments. This method is equivalent to:

((Comparable)obj1).compareTo(obj2)

Parameters

obj1:E: the first object to compare
obj2:E: the second object to compare

Returns:int

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

Annotations

@Override

Exceptions

NullPointerException:: if obj1 is null, or when ((Comparable)obj1).compareTo(obj2) does
ClassCastException:: if obj1 is not a Comparable, or when ((Comparable)obj1).compareTo(obj2) does

equals back to summary

equals	back to summary
public boolean equals(final Object object) Overrides java.lang.Object.equals. Implements java.util.Comparator.equals. Returns `true` iff that Object is is a `Comparator` whose ordering is known to be equivalent to mine. This implementation returns `true` iff `object.getClass()` equals `this.getClass()`. Subclasses may want to override this behavior to remain consistent with the `Comparator#equals(Object)` contract. Parameters object:Object the object to compare with Returns:boolean `true` if equal Annotations @Override Since 3.0

public boolean equals(final Object object)

Overrides java.lang.Object.equals.

Implements java.util.Comparator.equals.

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

This implementation returns true iff object.getClass() equals this.getClass(). Subclasses may want to override this behavior to remain consistent with the Comparator#equals(Object) contract.

Parameters

object:Object: the object to compare with

Returns:boolean

true if equal

Annotations

@Override

Since

3.0

hashCode back to summary

hashCode	back to summary
public int hashCode() Overrides java.lang.Object.hashCode. Implement a hash code for this comparator that is consistent with `equals`. Returns:int a hash code for this comparator. Annotations @Override Since 3.0

public int hashCode()

Overrides java.lang.Object.hashCode.

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

Returns:int

a hash code for this comparator.

Annotations

@Override

Since

3.0

public Class ComparableComparator<E extends java.lang.Comparable<? super E>>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail