java.lang.Object
- org.apache.commons.collections.comparators.BooleanComparator

All Implemented Interfaces:

Serializable, Comparator
```
public final class BooleanComparator
extends Object
implements Comparator, Serializable
```
A Comparator for Boolean objects that can sort either true or false first.

Since:

Commons Collections 3.0

Version:

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

Author:

Rodney Waldhoff

See Also:

getTrueFirstComparator(), getFalseFirstComparator(), getBooleanComparator(boolean), Serialized Form

Constructor Summary

Constructors
Constructor	Description
`BooleanComparator()`	Creates a `BooleanComparator` that sorts `false` values before `true` values.
`BooleanComparator(boolean trueFirst)`	Creates a `BooleanComparator` that sorts `trueFirst` values before `!trueFirst` values.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`compare(Boolean b1, Boolean b2)`	Compares two non-`null` `Boolean` objects according to the value of `sortsTrueFirst()`.
`int`	`compare(Object obj1, Object obj2)`	Compares two arbitrary Objects.
`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.

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

Methods inherited from interface java.util.Comparator
reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

- Constructor Detail
  - BooleanComparator
```
public BooleanComparator()
```
    Creates a BooleanComparator that sorts false values before true values.
    Equivalent to BooleanComparator(false).
    Please use the static factory instead whenever possible.
  - BooleanComparator
```
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
- Method Detail
  - getTrueFirstComparator
```
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
  - getFalseFirstComparator
```
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
  - getBooleanComparator
```
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
  - compare
```
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.
    
    Specified by:
    
    compare in interface Comparator
    
    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
  - compare
```
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
  - hashCode
```
public int hashCode()
```
    Implement a hash code for this comparator that is consistent with equals.
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    a hash code for this comparator.
  - equals
```
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.
    
    Specified by:
    
    equals in interface Comparator
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    object - the object to compare to
    
    Returns:
    
    true if equal
  - sortsTrueFirst
```
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

Class BooleanComparator

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Comparator

Constructor Detail

BooleanComparator

BooleanComparator

Method Detail

getTrueFirstComparator

getFalseFirstComparator

getBooleanComparator

compare

compare

hashCode

equals

sortsTrueFirst