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`.

  Since:
    JDK1.0
  Author:
    Arthur van Hoff
  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`.
    `static Class<Boolean>` | `TYPE` The Class object representing the primitive type boolean.

  - ### 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

    All Methods Static Methods Instance Methods Concrete 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, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### TRUE

          public static final Boolean TRUE

      The `Boolean` object corresponding to the primitive value `true`.

    - #### FALSE

          public static final Boolean FALSE

      The `Boolean` object corresponding to the primitive value `false`.

    - #### TYPE

          public static final Class<Boolean> TYPE

      The Class object representing the primitive type boolean.
      Since:
        JDK1.1

  - ### 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

    - #### 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
      Since:
        1.5

    - #### booleanValue

          public boolean booleanValue()

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

    - #### 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`.
      Since:
        1.4

    - #### 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.

    - #### 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`
      Since:
        1.4

    - #### 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.

    - #### 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)`

    - #### 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`

    - #### 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 JavaTM 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)`

    - #### 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`
      Since:
        1.5
      See Also:
        `Comparable`

    - #### 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`
      Since:
        1.7

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