1.public class Singleton {

private static class SingletonHolder {

public static Singleton resource = new Singleton();

public static Singleton getResource() {

return SingletonHolder.resource ;

private Singleton(){

2.public class Singleton {

public static final Singleton INSTANCE = new Singleton();

private Singleton(){} http://www.huiyi8.com/jiaoben/

public void method(){  

public static void main(String[] a){

//调用方法。

Singleton.INSTANCE.method();

3.* 利用枚举巧妙创建单实例

public enum Singleton {

INSTANCE;

public void method(){

public static void main(String[] a){

//调用方法。

Singleton.INSTANCE.method();

public class Singleton {

4. private static volatile Singleton instance = null;

* 防止其他人new对象

private Singleton(){

System.out.println("init");

public static Singleton getInstance(){

if(instance == null){

synchronized(Singleton.class){

if(instance == null){

instance = new Singleton();

return instance;