java.lang.Object
- org.apache.commons.collections.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:

Commons Collections 2.1

Version:

$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

Paul Jack, Stephen Colebourne

Field Summary

Fields
Modifier and Type Field Description

static Comparator NATURAL_COMPARATOR
Comparator for natural sort order.

Constructor Summary

Constructors
Constructor Description

ComparatorUtils()
ComparatorUtils should not normally be instantiated.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static Comparator`	`booleanComparator(boolean trueFirst)`	Gets a Comparator that can sort Boolean objects.
`static Comparator`	`chainedComparator(Collection 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 Comparator`	`chainedComparator(Comparator[] 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 Comparator`	`chainedComparator(Comparator comparator1, Comparator comparator2)`	Gets a comparator that compares using two `Comparator`s.
`static Object`	`max(Object o1, Object o2, Comparator comparator)`	Returns the larger of the given objects according to the given comparator, returning the second object if the comparator returns equal.
`static Object`	`min(Object o1, Object o2, Comparator comparator)`	Returns the smaller of the given objects according to the given comparator, returning the second object if the comparator returns equal.
`static Comparator`	`naturalComparator()`	Gets a comparator that uses the natural order of the objects.
`static Comparator`	`nullHighComparator(Comparator comparator)`	Gets a Comparator that controls the comparison of `null` values.
`static Comparator`	`nullLowComparator(Comparator comparator)`	Gets a Comparator that controls the comparison of `null` values.
`static Comparator`	`reversedComparator(Comparator comparator)`	Gets a comparator that reverses the order of the given comparator.
`static Comparator`	`transformedComparator(Comparator comparator, Transformer 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.getInstance()
- Constructor Detail
  - ComparatorUtils
```
public ComparatorUtils()
```
    ComparatorUtils should not normally be instantiated.
- Method Detail
  - naturalComparator
```
public static Comparator naturalComparator()
```
    Gets a comparator that uses the natural order of the objects.
    
    Returns:
    
    a comparator which uses natural order
  - chainedComparator
```
public static Comparator chainedComparator(Comparator comparator1,
                                           Comparator comparator2)
```
    Gets a comparator that compares using two Comparators.
    The second comparator is used if the first comparator returns equal.
    
    Parameters:
    
    comparator1 - the first comparator to use, not null
    
    comparator2 - the first comparator to use, not null
    
    Returns:
    
    a ComparatorChain formed from the two comparators
    
    Throws:
    
    NullPointerException - if either comparator is null
    
    See Also:
    
    ComparatorChain
  - chainedComparator
```
public static Comparator chainedComparator(Comparator[] 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:
    
    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 Comparator chainedComparator(Collection 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:
    
    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 Comparator reversedComparator(Comparator comparator)
```
    Gets a comparator that reverses the order of the given comparator.
    
    Parameters:
    
    comparator - the comparator to reverse
    
    Returns:
    
    a comparator that reverses the order of the input comparator
    
    See Also:
    
    ReverseComparator
  - booleanComparator
```
public static Comparator 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 Comparator nullLowComparator(Comparator 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:
    
    comparator - the comparator that wants to allow nulls
    
    Returns:
    
    a version of that comparator that allows nulls
    
    See Also:
    
    NullComparator
  - nullHighComparator
```
public static Comparator nullHighComparator(Comparator 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:
    
    comparator - the comparator that wants to allow nulls
    
    Returns:
    
    a version of that comparator that allows nulls
    
    See Also:
    
    NullComparator
  - transformedComparator
```
public static Comparator transformedComparator(Comparator comparator,
                                               Transformer 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:
    
    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 Object min(Object o1,
                         Object o2,
                         Comparator comparator)
```
    Returns the smaller of the given objects according to the given comparator, returning the second object if the comparator returns equal.
    
    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 Object max(Object o1,
                         Object o2,
                         Comparator comparator)
```
    Returns the larger of the given objects according to the given comparator, returning the second object if the comparator returns equal.
    
    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

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NATURAL_COMPARATOR

Constructor Detail

ComparatorUtils

Method Detail

naturalComparator

chainedComparator

chainedComparator

chainedComparator

reversedComparator

booleanComparator

nullLowComparator

nullHighComparator

transformedComparator

min

max