public final class

BooleanComparator

extends Object
implements Serializable Comparator<T>
java.lang.Object
   ↳ org.apache.commons.collections.comparators.BooleanComparator

Class Overview

A Comparator for Boolean objects that can sort either true or false first.

See Also

Summary

Public Constructors
BooleanComparator()
Creates a BooleanComparator that sorts false values before true values.
BooleanComparator(boolean trueFirst)
Creates a BooleanComparator that sorts trueFirst values before !trueFirst values.
Public Methods
int compare(Object obj1, Object obj2)
Compares two arbitrary Objects.
int compare(Boolean b1, Boolean b2)
Compares two non-null Boolean objects according to the value of sortsTrueFirst().
boolean equals(Object object)
Returns true iff that Object is is a Comparator whose ordering is known to be equivalent to mine.
static BooleanComparator getBooleanComparator(boolean trueFirst)
Returns a BooleanComparator instance that sorts trueFirst values before !trueFirst values.
static BooleanComparator getFalseFirstComparator()
Returns a BooleanComparator instance that sorts false values before true values.
static BooleanComparator getTrueFirstComparator()
Returns a BooleanComparator instance that sorts true values before false values.
int hashCode()
Implement a hash code for this comparator that is consistent with equals.
boolean sortsTrueFirst()
Returns true iff I sort true values before false values.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.util.Comparator

Public Constructors

public BooleanComparator ()

Creates a BooleanComparator that sorts false values before true values.

Equivalent to BooleanComparator(false).

Please use the static factory instead whenever possible.

public BooleanComparator (boolean trueFirst)

Creates a BooleanComparator that sorts trueFirst values before !trueFirst values.

Please use the static factories instead whenever possible.

Parameters
trueFirst when true, sort true boolean values before false

Public Methods

public int compare (Object obj1, Object obj2)

Compares two arbitrary Objects. When both arguments are Boolean, this method is equivalent to compare((Boolean)obj1,(Boolean)obj2). When either argument is not a Boolean, this methods throws a ClassCastException.

Parameters
obj1 the first object to compare
obj2 the second object to compare
Returns
  • negative if obj1 is less, positive if greater, zero if equal
Throws
ClassCastException when either argument is not Boolean

public int compare (Boolean b1, Boolean b2)

Compares two non-null Boolean objects according to the value of sortsTrueFirst().

Parameters
b1 the first boolean to compare
b2 the second boolean to compare
Returns
  • negative if obj1 is less, positive if greater, zero if equal
Throws
NullPointerException when either argument null

public boolean equals (Object object)

Returns true iff that Object is is a Comparator whose ordering is known to be equivalent to mine.

This implementation returns true iff that is a BooleanComparator whose value of sortsTrueFirst() is equal to mine.

Parameters
object the object to compare to
Returns
  • true if equal

public static BooleanComparator getBooleanComparator (boolean trueFirst)

Returns a BooleanComparator instance that sorts trueFirst values before !trueFirst values.

Clients are encouraged to use the value returned from this method instead of constructing a new instance to reduce allocation and garbage collection overhead when multiple BooleanComparators may be used in the same virtual machine.

Parameters
trueFirst when true, sort true Booleans before false
Returns
  • a singleton BooleanComparator instance

public static BooleanComparator getFalseFirstComparator ()

Returns a BooleanComparator instance that sorts false values before true values.

Clients are encouraged to use the value returned from this method instead of constructing a new instance to reduce allocation and garbage collection overhead when multiple BooleanComparators may be used in the same virtual machine.

Returns
  • the false first singleton BooleanComparator

public static BooleanComparator getTrueFirstComparator ()

Returns a BooleanComparator instance that sorts true values before false values.

Clients are encouraged to use the value returned from this method instead of constructing a new instance to reduce allocation and garbage collection overhead when multiple BooleanComparators may be used in the same virtual machine.

Returns
  • the true first singleton BooleanComparator

public int hashCode ()

Implement a hash code for this comparator that is consistent with equals.

Returns
  • a hash code for this comparator.

public boolean sortsTrueFirst ()

Returns true iff I sort true values before false values. In other words, returns true iff compare(Boolean.FALSE,Boolean.TRUE) returns a positive value.

Returns
  • the trueFirst flag