de.unkrig.commons.lang

Class Comparators

java.lang.Object

de.unkrig.commons.lang.Comparators

public final class Comparators
extends Object

Various Comparator-related utility methods.

Method Summary

Modifier and Type	Method and Description
static <T extends Comparable<T>> int	compareNullSafe(T c1, T c2)
static <T extends Comparable<T>> Comparator<T>	naturalOrderComparator()
static <T> Comparator<T>	nullSafeComparator(Comparator<T> delegate) Wraps the delegate comparator such that the cases "o1 == null" and/or "o2 == null" are detected and handled as follows: o1 == null && o2 == null 0 (as if o1.compareTo(o2) == 0) {@code o1 == null && o2 !

Methods inherited from class java.lang.Object

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

Method Detail

naturalOrderComparator

public static <T extends Comparable<T>> Comparator<T> naturalOrderComparator()

Returns:

A Comparator that compares subjects by their Comparable.compareTo(Object) method (and is thus not null-safe)

compareNullSafe

public static <T extends Comparable<T>> int compareNullSafe(@Nullable
                                                            T c1,
                                                            @Nullable
                                                            T c2)

Returns:

0 if both arguments are null, or -1 if only o1 is null, or 1 if only o2 is null, and otherwise o1.compareTo(o2)

nullSafeComparator

public static <T> Comparator<T> nullSafeComparator(Comparator<T> delegate)

Wraps the delegate comparator such that the cases "o1 == null" and/or "o2 == null" are detected and handled as follows:

o1 == null && o2 == null

0 (as if o1.compareTo(o2) == 0)

o1 == null && o2 != null

-1 (as if o1.compareTo(o2) < 0)

o1 != null && o2 == null

1 (as if o1.compareTo(o2) > 0)

o1 != null && o2 != null

delegate.compare(o1, o2)

The delegate is only invoked iff o1 != null && o2 != null.