单例模式——懒汉模式和饿汉模式

public class Test18 {

public static void main(String[] args) {
Single1 s1=Single1.getSingle1();
}

}
/**
* 饿汉模式
*/
class Single1{
private  Single1(){};
private static Single1 s1=new Single1();
public static Single1 getSingle1(){
return s1;
}
}
/**
* 懒汉模式
*/
class Single2{
private Single2(){};
private static Single2 s2=null;
public static Single2 getSingle2(){
if(s2==null){
s2=new Single2();
}
return s2;
}
}