设计模式-单例模式

public class SingletonDemo {public static void main(String[] args) {//饿汉式Singleton1 singleton1 = Singleton1.getInstance();singleton1.print();//懒汉式Singleton2 singleton2 = Singleton2.getInstance();singleton2.print();}}//饿汉式class Singleton1{private static Singleton1 singleton = new Singleton1();private Singleton1() {}public static synchronized Singleton1 getInstance() {return singleton;}public void print() {System.out.println("单例模式：饿汉式");}}//饿汉式class Singleton2{private static Singleton2 singleton = null;private Singleton2() {}public static Singleton2 getInstance() {if (singleton == null) {singleton = new Singleton2();}return singleton;}public void print() {System.out.println("单例模式：懒汉式");}}