ComparatorUtils

java.lang.Object
- org.apache.commons.collections4.ComparatorUtils

```
public class ComparatorUtils
extends Object
```
Provides convenient static utility methods for Comparator objects.
Most of the functionality in this class can also be found in the comparators package. This class merely provides a convenient central place if you have use for more than one class in the comparators subpackage.

Since:

2.1

Field Summary

Fields

Modifier and Type	Field and Description
`static Comparator`	`NATURAL_COMPARATOR` Comparator for natural sort order.

Method Summary

Methods

Modifier and Type	Method and Description
`static Comparator<Boolean>`	`booleanComparator(boolean trueFirst)` Gets a Comparator that can sort Boolean objects.
`static <E> Comparator<E>`	`chainedComparator(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.
`static <E> Comparator<E>`	`chainedComparator(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.
`static <E> E`	`max(E o1, 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.
`static <E> E`	`min(E o1, 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.
`static <E extends Comparable<? super E>> Comparator<E>`	`naturalComparator()` Gets a comparator that uses the natural order of the objects.
`static <E> Comparator<E>`	`nullHighComparator(Comparator<E> comparator)` Gets a Comparator that controls the comparison of `null` values.
`static <E> Comparator<E>`	`nullLowComparator(Comparator<E> comparator)` Gets a Comparator that controls the comparison of `null` values.
`static <E> Comparator<E>`	`reversedComparator(Comparator<E> comparator)` Gets a comparator that reverses the order of the given comparator.
`static <I,O> Comparator<I>`	`transformedComparator(Comparator<O> comparator, Transformer<? super I,? extends O> transformer)` Gets a Comparator that passes transformed objects to the given comparator.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - NATURAL_COMPARATOR
```
public static final Comparator NATURAL_COMPARATOR
```
    Comparator for natural sort order.
    
    See Also:
    
    ComparableComparator.comparableComparator()
- Method Detail
  - naturalComparator
```
public static <E extends Comparable<? super E>> Comparator<E> naturalComparator()
```
    Gets a comparator that uses the natural order of the objects.
    
    Type Parameters:
    
    E - the object type to compare
    
    Returns:
    
    a comparator which uses natural order
  - chainedComparator
```
public static <E> Comparator<E> chainedComparator(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.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    comparators - the comparators to use, not null or empty or containing nulls
    
    Returns:
    
    a ComparatorChain formed from the input comparators
    
    Throws:
    
    NullPointerException - if comparators array is null or contains a null
    
    See Also:
    
    ComparatorChain
  - chainedComparator
```
public static <E> Comparator<E> chainedComparator(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.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    comparators - the comparators to use, not null or empty or containing nulls
    
    Returns:
    
    a ComparatorChain formed from the input comparators
    
    Throws:
    
    NullPointerException - if comparators collection is null or contains a null
    
    ClassCastException - if the comparators collection contains the wrong object type
    
    See Also:
    
    ComparatorChain
  - reversedComparator
```
public static <E> Comparator<E> reversedComparator(Comparator<E> comparator)
```
    Gets a comparator that reverses the order of the given comparator.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    comparator - the comparator to reverse
    
    Returns:
    
    a comparator that reverses the order of the input comparator
    
    See Also:
    
    ReverseComparator
  - booleanComparator
```
public static Comparator<Boolean> booleanComparator(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 - when true, sort true Booleans before false Booleans.
    
    Returns:
    
    a comparator that sorts booleans
  - nullLowComparator
```
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.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    comparator - the comparator that wants to allow nulls
    
    Returns:
    
    a version of that comparator that allows nulls
    
    See Also:
    
    NullComparator
  - nullHighComparator
```
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.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    comparator - the comparator that wants to allow nulls
    
    Returns:
    
    a version of that comparator that allows nulls
    
    See Also:
    
    NullComparator
  - transformedComparator
```
public static <I,O> Comparator<I> transformedComparator(Comparator<O> comparator,
                                                        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.
    
    Type Parameters:
    
    I - the input object type of the transformed comparator
    
    O - the object type of the decorated comparator
    
    Parameters:
    
    comparator - the sort order to use
    
    transformer - the transformer to use
    
    Returns:
    
    a comparator that transforms its input objects before comparing them
    
    See Also:
    
    TransformingComparator
  - min
```
public static <E> E min(E o1,
                        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.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    o1 - the first object to compare
    
    o2 - the second object to compare
    
    comparator - the sort order to use
    
    Returns:
    
    the smaller of the two objects
  - max
```
public static <E> E max(E o1,
                        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.
    
    Type Parameters:
    
    E - the object type to compare
    
    Parameters:
    
    o1 - the first object to compare
    
    o2 - the second object to compare
    
    comparator - the sort order to use
    
    Returns:
    
    the larger of the two objects

Class ComparatorUtils

Field Summary

Fields

Method Summary

Methods

Methods inherited from class java.lang.Object

Field Detail

NATURAL_COMPARATOR

Method Detail

naturalComparator

chainedComparator

chainedComparator

reversedComparator

booleanComparator

nullLowComparator

nullHighComparator

transformedComparator

min

max