单例设计模式

单例设计模式

标准单例

public class Singleton{    private static final Singleton singleton = new Singleton();    private Singleton(){    }    public static Singleton getSingleton(){    return singleton;    }    //类中其他方法，尽量是static(因为getSingleton是static的)    public static void doSomething(){    }}

饿汉模式单例

public class Singleton{    private static final Singleton singleton = new Singleton();    private Singleton(){    }    public static Singleton getSingleton(){    return singleton;    }    public static void doSomething(){    }}

懒汉模式单例

public class Singleton{    private Singleton singleton = null;    private Singleton(){}    public static synchronized Singleton getSingleton(){        if(singleton == null){            singleton = new Singleton();        }        return singleton;    }}