https://openjdk.java.net/ 
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package java.lang;


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. 
Author: Arthur van Hoff
Since:  JDK1.0
/**
 * The Boolean class wraps a value of the primitive type
 * {@code boolean} in an object. An object of type
 * {@code Boolean} contains a single field whose type is
 * {@code boolean}.
 * <p>
 * In addition, this class provides many methods for
 * converting a {@code boolean} to a {@code String} and a
 * {@code String} to a {@code boolean}, as well as other
 * constants and methods useful when dealing with a
 * {@code boolean}.
 *
 * @author  Arthur van Hoff
 * @since   JDK1.0
 */
public final class Boolean implements java.io.Serializable,
                                      Comparable<Boolean>
{
    
The Boolean object corresponding to the primitive value true. 
/**
     * The {@code Boolean} object corresponding to the primitive
     * value {@code true}.
     */
    public static final Boolean TRUE = new Boolean(true);

    
The Boolean object corresponding to the primitive value false. 
/**
     * The {@code Boolean} object corresponding to the primitive
     * value {@code false}.
     */
    public static final Boolean FALSE = new Boolean(false);

    
The Class object representing the primitive type boolean.

Since:  JDK1.1
/**
     * The Class object representing the primitive type boolean.
     *
     * @since   JDK1.1
     */
    public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean");

    
The value of the Boolean.

@serial
/**
     * The value of the Boolean.
     *
     * @serial
     */
    private final boolean value;

    
use serialVersionUID from JDK 1.0.2 for interoperability 
/** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = -3665804199014368530L;

    
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.

Params:
  • value –  the value of the Boolean.
/**
     * Allocates a {@code Boolean} object representing the
     * {@code value} argument.
     *
     * <p><b>Note: It is rarely appropriate to use this constructor.
     * Unless a <i>new</i> instance is required, the static factory
     * {@link #valueOf(boolean)} is generally a better choice. It is
     * likely to yield significantly better space and time performance.</b>
     *
     * @param   value   the value of the {@code Boolean}.
     */
    public Boolean(boolean value) {
        this.value = value;
    }

    
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. 
Params:
  • s –  the string to be converted to a Boolean.
/**
     * Allocates a {@code Boolean} object representing the value
     * {@code true} if the string argument is not {@code null}
     * and is equal, ignoring case, to the string {@code "true"}.
     * Otherwise, allocate a {@code Boolean} object representing the
     * value {@code false}. Examples:<p>
     * {@code new Boolean("True")} produces a {@code Boolean} object
     * that represents {@code true}.<br>
     * {@code new Boolean("yes")} produces a {@code Boolean} object
     * that represents {@code false}.
     *
     * @param   s   the string to be converted to a {@code Boolean}.
     */
    public Boolean(String s) {
        this(toBoolean(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. 
Params:
  • s –  the String containing the boolean representation to be parsed
Returns:    the boolean represented by the string argument
Since:1.5
/**
     * Parses the string argument as a boolean.  The {@code boolean}
     * returned represents the value {@code true} if the string argument
     * is not {@code null} and is equal, ignoring case, to the string
     * {@code "true"}. <p>
     * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
     * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
     *
     * @param      s   the {@code String} containing the boolean
     *                 representation to be parsed
     * @return     the boolean represented by the string argument
     * @since 1.5
     */
    public static boolean parseBoolean(String s) {
        return toBoolean(s);
    }

    
Returns the value of this Boolean object as a boolean primitive. 
Returns: the primitive boolean value of this object.
/**
     * Returns the value of this {@code Boolean} object as a boolean
     * primitive.
     *
     * @return  the primitive {@code boolean} value of this object.
     */
    public boolean booleanValue() {
        return value;
    }

    
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. 
Params:
  • b – a boolean value.
Returns:a Boolean instance representing b.
Since: 1.4
/**
     * Returns a {@code Boolean} instance representing the specified
     * {@code boolean} value.  If the specified {@code boolean} value
     * is {@code true}, this method returns {@code Boolean.TRUE};
     * if it is {@code false}, this method returns {@code Boolean.FALSE}.
     * If a new {@code Boolean} instance is not required, this method
     * should generally be used in preference to the constructor
     * {@link #Boolean(boolean)}, as this method is likely to yield
     * significantly better space and time performance.
     *
     * @param  b a boolean value.
     * @return a {@code Boolean} instance representing {@code b}.
     * @since  1.4
     */
    public static Boolean valueOf(boolean b) {
        return (b ? TRUE : FALSE);
    }

    
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". 
Params:
  • s –   a string.
Returns: the Boolean value represented by the string.
/**
     * Returns a {@code Boolean} with a value represented by the
     * specified string.  The {@code Boolean} returned represents a
     * true value if the string argument is not {@code null}
     * and is equal, ignoring case, to the string {@code "true"}.
     *
     * @param   s   a string.
     * @return  the {@code Boolean} value represented by the string.
     */
    public static Boolean valueOf(String s) {
        return toBoolean(s) ? TRUE : FALSE;
    }

    
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. 
Params:
  • b – the boolean to be converted
Returns:the string representation of the specified boolean
Since:1.4
/**
     * Returns a {@code String} object representing the specified
     * boolean.  If the specified boolean is {@code true}, then
     * the string {@code "true"} will be returned, otherwise the
     * string {@code "false"} will be returned.
     *
     * @param b the boolean to be converted
     * @return the string representation of the specified {@code boolean}
     * @since 1.4
     */
    public static String toString(boolean b) {
        return b ? "true" : "false";
    }

    
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. 
Returns: a string representation of this object.
/**
     * Returns a {@code String} object representing this Boolean's
     * value.  If this object represents the value {@code true},
     * a string equal to {@code "true"} is returned. Otherwise, a
     * string equal to {@code "false"} is returned.
     *
     * @return  a string representation of this object.
     */
    public String toString() {
        return value ? "true" : "false";
    }

    
Returns a hash code for this Boolean object. 
Returns: the integer 1231 if this object represents true; returns the integer 1237 if this object represents false.
/**
     * Returns a hash code for this {@code Boolean} object.
     *
     * @return  the integer {@code 1231} if this object represents
     * {@code true}; returns the integer {@code 1237} if this
     * object represents {@code false}.
     */
    public int hashCode() {
        return value ? 1231 : 1237;
    }

    
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. 
Params:
  • obj –   the object to compare with.
Returns: true if the Boolean objects represent the same value; false otherwise.
/**
     * Returns {@code true} if and only if the argument is not
     * {@code null} and is a {@code Boolean} object that
     * represents the same {@code boolean} value as this object.
     *
     * @param   obj   the object to compare with.
     * @return  {@code true} if the Boolean objects represent the
     *          same value; {@code false} otherwise.
     */
    public boolean equals(Object obj) {
        if (obj instanceof Boolean) {
            return value == ((Boolean)obj).booleanValue();
        }
        return false;
    }

    
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. 
Params:
  • name –   the system property name.
See Also:
Returns: the boolean value of the system property.
/**
     * Returns {@code true} if and only if the system property
     * named by the argument exists and is equal to the string
     * {@code "true"}. (Beginning with version 1.0.2 of the
     * Java<small><sup>TM</sup></small> platform, the test of
     * this string is case insensitive.) A system property is accessible
     * through {@code getProperty}, a method defined by the
     * {@code System} class.
     * <p>
     * If there is no property with the specified name, or if the specified
     * name is empty or null, then {@code false} is returned.
     *
     * @param   name   the system property name.
     * @return  the {@code boolean} value of the system property.
     * @see     java.lang.System#getProperty(java.lang.String)
     * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
     */
    public static boolean getBoolean(String name) {
        boolean result = false;
        try {
            result = toBoolean(System.getProperty(name));
        } catch (IllegalArgumentException e) {
        } catch (NullPointerException e) {
        }
        return result;
    }

    
Compares this Boolean instance with another. 
Params:
  • b – the Boolean instance to be compared
Throws:
See Also:
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
Since: 1.5
/**
     * Compares this {@code Boolean} instance with another.
     *
     * @param   b the {@code Boolean} instance to be compared
     * @return  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 {@code null}
     * @see     Comparable
     * @since  1.5
     */
    public int compareTo(Boolean b) {
        return (b.value == value ? 0 : (value ? 1 : -1));
    }

    private static boolean toBoolean(String name) {
        return ((name != null) && name.equalsIgnoreCase("true"));
    }
}