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 Note: It is rarely appropriate to use this constructor.
* Unless a new 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.
*
* @param value the value of the
* new Boolean("True") produces a Boolean object
* that represents true.
* Example: Boolean.valueOf("True") returns true.
* If there is no property with the specified name, or if the specified
* name is empty or null, then 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
* @version 1.51, 05/11/04
* @since JDK1.0
*/
public final class Boolean implements java.io.Serializable,
ComparableBoolean object corresponding to the primitive
* value true.
*/
public static final Boolean TRUE = new Boolean(true);
/**
* The Boolean object corresponding to the primitive
* value false.
*/
public static final Boolean FALSE = new Boolean(false);
/**
* The Class object representing the primitive type boolean.
*
* @since JDK1.1
*/
public static final ClassBoolean object representing the
* value argument.
*
* 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("yes") produces a Boolean object
* that represents false.
*
* @param s the string to be converted to a 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".
*
* @param s the 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.
*
* @return the primitive 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
* {@link #Boolean(boolean)}, as this method is likely to yield
* significantly better space and time performance.
*
* @param b a boolean value.
* @return a Boolean instance representing 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 the
* value true if the string argument is not null
* and is equal, ignoring case, to the string "true".
* Example: Boolean.valueOf("yes") returns false.
*
* @param s a string.
* @return the 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.
*
* @param b the boolean to be converted
* @return the string representation of the specified 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.
*
* @return a string representation of this object.
*/
public String toString() {
return value ? "true" : "false";
}
/**
* Returns a hash code for this Boolean object.
*
* @return the integer 1231 if this object represents
* true; returns the integer 1237 if this
* object represents 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.
*
* @param obj the object to compare with.
* @return true if the Boolean objects represent the
* same value; 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.
* false is returned.
*
* @param name the system property name.
* @return the 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.
*
* @param b the 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 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"));
}
}