BooleanComparator (Apache Commons Collections 3.2.2 API)

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: 972404 $ $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 and 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

Methods
Modifier and Type	Method and 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

- 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

Constructor Detail

BooleanComparator

BooleanComparator

Method Detail

getTrueFirstComparator

getFalseFirstComparator

getBooleanComparator

compare

compare

hashCode

equals

sortsTrueFirst