03 java.lang.Boolean

Boolean

2015.01.10
By 970655147

声明

/**
* 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>

Boolean的属性(们)

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

/**
* 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
*/

public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean");
/**
* The value of the Boolean.
*
* @serial
private final boolean value;

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

Boolean. parseBoolean(String s)

public static boolean parseBoolean(String s) {
return toBoolean(s);
}

private static boolean toBoolean(String name) {
// 如果字符串不为null并且不为“true/TRUE”就返回true
return ((name != null) && name.equalsIgnoreCase("true"));
}

Boolean. booleanValue()

public boolean booleanValue() {
// 返回封装的boolean值
return value;
}

Boolean. valueOf(boolean b)

public static Boolean valueOf(boolean b) {
// 如果b是true 返回TRUE对象 否则返回FALSE对象
return (b ? TRUE : FALSE);
}

public static Boolean valueOf(String s) {
// 如果s是true 则返回TRUE对象 否则返回FALSE对象
return toBoolean(s) ? TRUE : FALSE;
}

Boolean. toString()

public static String toString(boolean b) {
// 如果b是true 返回“true” 否则返回“false”
return b ? "true" : "false";
}

public String toString() {
// 如果封装的value是true 返回“true” 否则返回“false”
return value ? "true" : "false";
}

Boolean. hashCode()

public int hashCode() {
// 如果封装的value是true hash值是1231 否则返回hash值是1237
return value ? 1231 : 1237;
}

Boolean. equals(Object obj)

public boolean equals(Object obj) {
// RTTI 判断obj是否是Boolean或者是其子类
if (obj instanceof Boolean) {
return value == ((Boolean)obj).booleanValue();
}
return false;
}

Boolean. getBoolean(String name)

// 获取系统属性的Boolean值
public static boolean getBoolean(String name) {
boolean result = false;
try {
result = toBoolean(System.getProperty(name));
} catch (IllegalArgumentException e) {
} catch (NullPointerException e) {
}
return result;
}

Boolean. compareTo(Boolean b)

public int compareTo(Boolean b) {
return compare(this.value, b.value);
}

public static int compare(boolean x, boolean y) {
// 如果x==y 返回0 否则如果x为ture返回1 x为false返回-1
return (x == y) ? 0 : (x ? 1 : -1);
}