单例模式

package com.war3;

public class Singleton {

    private static final Singleton singleton = new Singleton();
    
    private Singleton(){}
    
    public static Singleton getInstance(){
        return singleton;
    }
}

package com.war3;

public class Test {

    public static void main(String[] args) {
        
        Singleton s1= Singleton.getInstance();
        Singleton s2= Singleton.getInstance();
        System.out.println(s1==s2);//true
    }
}