java.lang

Class Boolean

java.lang.Object

java.lang.Boolean

All Implemented Interfaces:

Serializable, Comparable<Boolean>

public final class Boolean
extends Object
implements Serializable, Comparable<Boolean>

The Boolean class wraps a value of the primitive type boolean in an object. An object of type Boolean contains a single field whose type is boolean.

In addition, this class provides many methods for converting a boolean to a String and a String to a boolean, as well as other constants and methods useful when dealing with a boolean.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static Boolean	FALSE The Boolean object corresponding to the primitive value false.
static Boolean	TRUE The Boolean object corresponding to the primitive value true.

Constructor Summary

Constructors

Constructor and Description
Boolean(boolean value) Allocates a Boolean object representing the value argument.
Boolean(String s) Allocates a Boolean object representing the value true if the string argument is not null and is equal, ignoring case, to the string "true".

Method Summary

Methods

Modifier and Type	Method and Description
boolean	booleanValue() Returns the value of this Boolean object as a boolean primitive.
static int	compare(boolean x, boolean y) Compares two boolean values.
int	compareTo(Boolean b) Compares this Boolean instance with another.
boolean	equals(Object obj) Returns true if and only if the argument is not null and is a Boolean object that represents the same boolean value as this object.
static boolean	getBoolean(String name) Returns true if and only if the system property named by the argument exists and is equal to the string "true".
int	hashCode() Returns a hash code for this Boolean object.
static boolean	parseBoolean(String s) Parses the string argument as a boolean.
String	toString() Returns a String object representing this Boolean's value.
static String	toString(boolean b) Returns a String object representing the specified boolean.
static Boolean	valueOf(boolean b) Returns a Boolean instance representing the specified boolean value.
static Boolean	valueOf(String s) Returns a Boolean with a value represented by the specified string.

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, wait, wait, wait

Field Detail

FALSE

public static final Boolean FALSE

The Boolean object corresponding to the primitive value false.

TRUE

public static final Boolean TRUE

The Boolean object corresponding to the primitive value true.

Constructor Detail

Boolean

public Boolean(boolean value)

Allocates a Boolean object representing the value argument.

Note: It is rarely appropriate to use this constructor. Unless a new instance is required, the static factory valueOf(boolean) is generally a better choice. It is likely to yield significantly better space and time performance.

Parameters:

value - the value of the Boolean.

Boolean

public Boolean(String s)

Allocates a Boolean object representing the value true if the string argument is not null and is equal, ignoring case, to the string "true". Otherwise, allocate a Boolean object representing the value false. Examples:

new Boolean("True") produces a Boolean object that represents true.
new Boolean("yes") produces a Boolean object that represents false.

Parameters:

s - the string to be converted to a Boolean.

Method Detail

compare

public static int compare(boolean x,
          boolean y)

Compares two boolean values. The value returned is identical to what would be returned by:

 Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
 

Parameters:

x - the first boolean to compare

y - the second boolean to compare

Returns:

the value 0 if x == y; a value less than 0 if !x && y ; and a value greater than 0 if x && !y

getBoolean

public static boolean getBoolean(String name)

Returns true if and only if the system property named by the argument exists and is equal to the string "true". (Beginning with version 1.0.2 of the Java^TM platform, the test of this string is case insensitive.) A system property is accessible through getProperty, a method defined by the System class.

If there is no property with the specified name, or if the specified name is empty or null, then false is returned.

Parameters:

name - the system property name.

Returns:

the boolean value of the system property.

See Also:

System.getProperty(java.lang.String), System.getProperty(java.lang.String, java.lang.String)

parseBoolean

public static boolean parseBoolean(String s)

Parses the string argument as a boolean. The boolean returned represents the value true if the string argument is not null and is equal, ignoring case, to the string "true".

Example: Boolean.parseBoolean("True") returns true.
Example: Boolean.parseBoolean("yes") returns false.

Parameters:

s - the String containing the boolean representation to be parsed

Returns:

the boolean represented by the string argument

toString

public static String toString(boolean b)

Returns a String object representing the specified boolean. If the specified boolean is true, then the string "true" will be returned, otherwise the string "false" will be returned.

Parameters:

b - the boolean to be converted

Returns:

the string representation of the specified boolean

valueOf

public static Boolean valueOf(boolean b)

Returns a Boolean instance representing the specified boolean value. If the specified boolean value is true, this method returns Boolean.TRUE; if it is false, this method returns Boolean.FALSE. If a new Boolean instance is not required, this method should generally be used in preference to the constructor Boolean(boolean), as this method is likely to yield significantly better space and time performance.

Parameters:

b - a boolean value.

Returns:

a Boolean instance representing b.

valueOf

public static Boolean valueOf(String s)

Returns a Boolean with a value represented by the specified string. The Boolean returned represents a true value if the string argument is not null and is equal, ignoring case, to the string "true".

Parameters:

s - a string.

Returns:

the Boolean value represented by the string.

booleanValue

public boolean booleanValue()

Returns the value of this Boolean object as a boolean primitive.

Returns:

the primitive boolean value of this object.

compareTo

public int compareTo(Boolean b)

Compares this Boolean instance with another.

Specified by:

compareTo in interface Comparable<Boolean>

Parameters:

b - the Boolean instance to be compared

Returns:

zero if this object represents the same boolean value as the argument; a positive value if this object represents true and the argument represents false; and a negative value if this object represents false and the argument represents true

Throws:

NullPointerException - if the argument is null

See Also:

Comparable

equals

public boolean equals(Object obj)

Returns true if and only if the argument is not null and is a Boolean object that represents the same boolean value as this object.

Overrides:

equals in class Object

Parameters:

obj - the object to compare with.

Returns:

true if the Boolean objects represent the same value; false otherwise.

See Also:

Object.hashCode(), HashMap

hashCode

public int hashCode()

Returns a hash code for this Boolean object.

Overrides:

hashCode in class Object

Returns:

the integer 1231 if this object represents true; returns the integer 1237 if this object represents false.

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

toString

public String toString()

Returns a String object representing this Boolean's value. If this object represents the value true, a string equal to "true" is returned. Otherwise, a string equal to "false" is returned.

Overrides:

toString in class Object

Returns:

a string representation of this object.