org.apache.commons.collections
Class ComparatorUtils
java.lang.Object
org.apache.commons.collections.ComparatorUtils
public class ComparatorUtils
extends java.lang.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.
- Paul Jack
- Stephen Colebourne
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 comparator1, Comparator comparator2) - Gets a comparator that compares using two
Comparator s.
|
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 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.
|
NATURAL_COMPARATOR
public static final Comparator NATURAL_COMPARATOR
Comparator for natural sort order.
ComparatorUtils
public ComparatorUtils()
ComparatorUtils should not normally be instantiated.
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.
trueFirst
- when true
, sort
true
Boolean
s before
false
Boolean
s.
- a comparator that sorts booleans
chainedComparator
public 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.
comparators
- the comparators to use, not null or empty or containing nulls
chainedComparator
public static Comparator chainedComparator(Comparator comparator1,
Comparator comparator2)
Gets a comparator that compares using two
Comparator
s.
The second comparator is used if the first comparator returns equal.
comparator1
- the first comparator to use, not nullcomparator2
- the first comparator to use, not null
chainedComparator
public 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.
comparators
- the comparators to use, not null or empty or containing nulls
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.
o1
- the first object to compareo2
- the second object to comparecomparator
- the sort order to use
- the larger of the two objects
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.
o1
- the first object to compareo2
- the second object to comparecomparator
- the sort order to use
- the smaller of the two objects
naturalComparator
public static Comparator naturalComparator()
Gets a comparator that uses the natural order of the objects.
- a comparator which uses natural order
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.
comparator
- the comparator that wants to allow nulls
- a version of that comparator that allows nulls
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.
comparator
- the comparator that wants to allow nulls
- a version of that comparator that allows nulls
reversedComparator
public static Comparator reversedComparator(Comparator comparator)
Gets a comparator that reverses the order of the given comparator.
comparator
- the comparator to reverse
- a comparator that reverses the order of the input comparator
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.
comparator
- the sort order to usetransformer
- the transformer to use
- a comparator that transforms its input objects before comparing them
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