单例模式要点是:一个类必须只能一个实例;自己提供创建该类的方法;该方法和类里的实例化对象,由于不能外部实例化,所以static修饰;
其中有饱汉模式和饿汉模式;
饱汉-------
public class Singleton {
private static Singleton singleton = new Singleton ( ) ;
private Singleton ( ) { }
public static Singleton getInstance ( ) {
return singleton ;
}
}
饿汉-----
public class Singleton {
private static Singleton singleton ;
private Singleton ( ) { }
public static synchronized Singleton getInstance ( ) {
if ( singleton == null ) {
singleton = new Singleton ( ) ;
}
return singleton ;
}
}