Apache Commons Collections 4.4 · org.apache.commons.collections4.ComparatorUtils

Modifier and Type	Field and Description
public static final Comparator<T>	NATURAL_COMPARATOR Comparator for natural sort order.

Access	Constructor and Description
private	ComparatorUtils() ComparatorUtils should not normally be instantiated.

Method Summary

Modifier and Type	Method and Description
public static Comparator<Boolean>	Returns: a comparator that sorts booleans booleanComparator(final boolean when `true`, sort `true` `Boolean`s before `false` `Boolean`s. trueFirst) Gets a Comparator that can sort Boolean objects.
public static < the object type to compare E> Comparator<E>	Returns: a `ComparatorChain` formed from the input comparators chainedComparator(final Comparator<E>... the comparators to use, not null or empty or containing nulls comparators) Gets a comparator that compares using an array of `Comparator`s, applied in sequence until one returns not equal or the array is exhausted.
public static < the object type to compare E> Comparator<E>	Returns: a `ComparatorChain` formed from the input comparators chainedComparator(final Collection<Comparator<E>> the comparators to use, not null or empty or containing nulls comparators) Gets a comparator that compares using a collection of `Comparator`s, applied in (default iterator) sequence until one returns not equal or the collection is exhausted.
public static < the object type to compare E> E	Returns: the larger of the two objects max(final E the first object to compare o1, final E the second object to compare o2, Comparator<E> the sort order to use comparator) Returns the larger of the given objects according to the given comparator, returning the second object if the comparator returns equal.
public static < the object type to compare E> E	Returns: the smaller of the two objects min(final E the first object to compare o1, final E the second object to compare o2, Comparator<E> the sort order to use comparator) Returns the smaller of the given objects according to the given comparator, returning the second object if the comparator returns equal.
public static < the object type to compare E extends Comparable<? super E>> Comparator<E>	Returns: a comparator which uses natural order naturalComparator() Gets a comparator that uses the natural order of the objects.
public static < the object type to compare E> Comparator<E>	Returns: a version of that comparator that allows nulls nullHighComparator(Comparator<E> the comparator that wants to allow nulls comparator) Gets a Comparator that controls the comparison of `null` values.
public static < the object type to compare E> Comparator<E>	Returns: a version of that comparator that allows nulls nullLowComparator(Comparator<E> the comparator that wants to allow nulls comparator) Gets a Comparator that controls the comparison of `null` values.
public static < the object type to compare E> Comparator<E>	Returns: a comparator that reverses the order of the input comparator reversedComparator(final Comparator<E> the comparator to reverse comparator) Gets a comparator that reverses the order of the given comparator.
public static < the input object type of the transformed comparator I, the object type of the decorated comparator O> Comparator<I>	Returns: a comparator that transforms its input objects before comparing them transformedComparator(Comparator<O> the sort order to use comparator, final Transformer<? super I, ? extends O> the transformer to use transformer) Gets a Comparator that passes transformed objects to the given comparator.

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

NATURAL_COMPARATOR	back to summary
public static final Comparator<T> NATURAL_COMPARATOR Comparator for natural sort order. Annotations @SuppressWarnings:rawtypes, unchecked See Also `ComparableComparator#comparableComparator()`

ComparatorUtils	back to summary
private ComparatorUtils() ComparatorUtils should not normally be instantiated.

Method Detail

booleanComparator back to summary

booleanComparator	back to summary
public static Comparator<Boolean> booleanComparator(final boolean trueFirst) Gets a Comparator that can sort Boolean objects. The parameter specifies whether true or false is sorted first. The comparator throws NullPointerException if a null value is compared. Parameters trueFirst:boolean when `true`, sort `true` `Boolean`s before `false` `Boolean`s. Returns:Comparator<Boolean> a comparator that sorts booleans

public static Comparator<Boolean> booleanComparator(final boolean trueFirst)

Gets a Comparator that can sort Boolean objects.

The parameter specifies whether true or false is sorted first.

The comparator throws NullPointerException if a null value is compared.

Parameters

trueFirst:boolean: when true, sort true Booleans before false Booleans.

Returns:Comparator<Boolean>

a comparator that sorts booleans

chainedComparator back to summary

chainedComparator	back to summary
public static <E> Comparator<E> chainedComparator(final Comparator<E>... comparators) Gets a comparator that compares using an array of `Comparator`s, applied in sequence until one returns not equal or the array is exhausted. Parameters <E> the object type to compare comparators:Comparator<E>[] the comparators to use, not null or empty or containing nulls Returns:Comparator<E> a `ComparatorChain` formed from the input comparators Exceptions NullPointerException: if comparators array is null or contains a null See Also `ComparatorChain`

public static <E> Comparator<E> chainedComparator(final Comparator<E>... comparators)

Gets a comparator that compares using an array of Comparators, applied in sequence until one returns not equal or the array is exhausted.

Parameters

<E>: the object type to compare
comparators:Comparator<E>[]: the comparators to use, not null or empty or containing nulls

Returns:Comparator<E>

a ComparatorChain formed from the input comparators

Exceptions

NullPointerException:: if comparators array is null or contains a null

See Also

ComparatorChain

chainedComparator back to summary

chainedComparator	back to summary
public static <E> Comparator<E> chainedComparator(final Collection<Comparator<E>> comparators) Gets a comparator that compares using a collection of `Comparator`s, applied in (default iterator) sequence until one returns not equal or the collection is exhausted. Parameters <E> the object type to compare comparators:Collection<Comparator<E>> the comparators to use, not null or empty or containing nulls Returns:Comparator<E> a `ComparatorChain` formed from the input comparators Annotations @SuppressWarnings:unchecked Exceptions NullPointerException: if comparators collection is null or contains a null ClassCastException: if the comparators collection contains the wrong object type See Also `ComparatorChain`

public static <E> Comparator<E> chainedComparator(final Collection<Comparator<E>> comparators)

Gets a comparator that compares using a collection of Comparators, applied in (default iterator) sequence until one returns not equal or the collection is exhausted.

Parameters

<E>: the object type to compare
comparators:Collection<Comparator<E>>: the comparators to use, not null or empty or containing nulls

Returns:Comparator<E>

a ComparatorChain formed from the input comparators

Annotations

@SuppressWarnings:unchecked

Exceptions

NullPointerException:: if comparators collection is null or contains a null
ClassCastException:: if the comparators collection contains the wrong object type

See Also

ComparatorChain

max	back to summary
public static <E> E max(final E o1, final E o2, Comparator<E> comparator) Returns the larger of the given objects according to the given comparator, returning the second object if the comparator returns equal. Parameters <E> the object type to compare o1:E the first object to compare o2:E the second object to compare comparator:Comparator<E> the sort order to use Returns:E the larger of the two objects Annotations @SuppressWarnings:unchecked

max

back to summary

public static <E> E max(final E o1, final E o2, Comparator<E> comparator)

Returns the larger of the given objects according to the given comparator, returning the second object if the comparator returns equal.

Parameters

<E>: the object type to compare
o1:E: the first object to compare
o2:E: the second object to compare
comparator:Comparator<E>: the sort order to use

Returns:E

the larger of the two objects

Annotations

@SuppressWarnings:unchecked

min	back to summary
public static <E> E min(final E o1, final E o2, Comparator<E> comparator) Returns the smaller of the given objects according to the given comparator, returning the second object if the comparator returns equal. Parameters <E> the object type to compare o1:E the first object to compare o2:E the second object to compare comparator:Comparator<E> the sort order to use Returns:E the smaller of the two objects Annotations @SuppressWarnings:unchecked

min

back to summary

public static <E> E min(final E o1, final E o2, Comparator<E> comparator)

Returns the smaller of the given objects according to the given comparator, returning the second object if the comparator returns equal.

Parameters

<E>: the object type to compare
o1:E: the first object to compare
o2:E: the second object to compare
comparator:Comparator<E>: the sort order to use

Returns:E

the smaller of the two objects

Annotations

@SuppressWarnings:unchecked

naturalComparator	back to summary
public static <E extends Comparable<? super E>> Comparator<E> naturalComparator() Gets a comparator that uses the natural order of the objects. Parameters <E> the object type to compare Returns:Comparator<E> a comparator which uses natural order Annotations @SuppressWarnings:unchecked

naturalComparator

back to summary

public static <E extends Comparable<? super E>> Comparator<E> naturalComparator()

Gets a comparator that uses the natural order of the objects.

Parameters

<E>: the object type to compare

Returns:Comparator<E>

a comparator which uses natural order

Annotations

@SuppressWarnings:unchecked

nullHighComparator back to summary

nullHighComparator	back to summary
public static <E> Comparator<E> nullHighComparator(Comparator<E> comparator) Gets a Comparator that controls the comparison of `null` values. The returned comparator will consider a null value to be greater than any nonnull value, and equal to any other null value. Two nonnull values will be evaluated with the given comparator. Parameters <E> the object type to compare comparator:Comparator<E> the comparator that wants to allow nulls Returns:Comparator<E> a version of that comparator that allows nulls Annotations @SuppressWarnings:unchecked See Also `NullComparator`

public static <E> Comparator<E> nullHighComparator(Comparator<E> comparator)

Gets a Comparator that controls the comparison of null values.

The returned comparator will consider a null value to be greater than any nonnull value, and equal to any other null value. Two nonnull values will be evaluated with the given comparator.

Parameters

<E>: the object type to compare
comparator:Comparator<E>: the comparator that wants to allow nulls

Returns:Comparator<E>

a version of that comparator that allows nulls

Annotations

@SuppressWarnings:unchecked

See Also

NullComparator

nullLowComparator back to summary

nullLowComparator	back to summary
public static <E> Comparator<E> nullLowComparator(Comparator<E> comparator) Gets a Comparator that controls the comparison of `null` values. The returned comparator will consider a null value to be less than any nonnull value, and equal to any other null value. Two nonnull values will be evaluated with the given comparator. Parameters <E> the object type to compare comparator:Comparator<E> the comparator that wants to allow nulls Returns:Comparator<E> a version of that comparator that allows nulls Annotations @SuppressWarnings:unchecked See Also `NullComparator`

public static <E> Comparator<E> nullLowComparator(Comparator<E> comparator)

Gets a Comparator that controls the comparison of null values.

The returned comparator will consider a null value to be less than any nonnull value, and equal to any other null value. Two nonnull values will be evaluated with the given comparator.

Parameters

<E>: the object type to compare
comparator:Comparator<E>: the comparator that wants to allow nulls

Returns:Comparator<E>

a version of that comparator that allows nulls

Annotations

@SuppressWarnings:unchecked

See Also

NullComparator

reversedComparator back to summary

reversedComparator	back to summary
public static <E> Comparator<E> reversedComparator(final Comparator<E> comparator) Gets a comparator that reverses the order of the given comparator. Parameters <E> the object type to compare comparator:Comparator<E> the comparator to reverse Returns:Comparator<E> a comparator that reverses the order of the input comparator See Also `ReverseComparator`

public static <E> Comparator<E> reversedComparator(final Comparator<E> comparator)

Gets a comparator that reverses the order of the given comparator.

Parameters

<E>: the object type to compare
comparator:Comparator<E>: the comparator to reverse

Returns:Comparator<E>

a comparator that reverses the order of the input comparator

See Also

ReverseComparator

transformedComparator back to summary

transformedComparator	back to summary
public static <I, O> Comparator<I> transformedComparator(Comparator<O> comparator, final Transformer<? super I, ? extends O> transformer) Gets a Comparator that passes transformed objects to the given comparator. Objects passed to the returned comparator will first be transformed by the given transformer before they are compared by the given comparator. Parameters <I> the input object type of the transformed comparator <O> the object type of the decorated comparator comparator:Comparator<O> the sort order to use transformer:Transformer<? super I, ? extends O> the transformer to use Returns:Comparator<I> a comparator that transforms its input objects before comparing them Annotations @SuppressWarnings:unchecked See Also `TransformingComparator`

public static <I, O> Comparator<I> transformedComparator(Comparator<O> comparator, final Transformer<? super I, ? extends O> transformer)

Gets a Comparator that passes transformed objects to the given comparator.

Objects passed to the returned comparator will first be transformed by the given transformer before they are compared by the given comparator.

Parameters

<I>: the input object type of the transformed comparator
<O>: the object type of the decorated comparator
comparator:Comparator<O>: the sort order to use
transformer:Transformer<? super I, ? extends O>: the transformer to use

Returns:Comparator<I>

a comparator that transforms its input objects before comparing them

Annotations

@SuppressWarnings:unchecked

See Also

TransformingComparator

public Class ComparatorUtils

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