Java 单例设计模式

public class SingleTon {
    
    // 1. 饿汉式
    

    // 2. 懒汉式
    
    private volatile static SingleTon singleTon;

    private SingleTon(){}

    public SingleTon getSingleTon(){
        if(singleTon == null){
            synchronized (SingleTon.class){
                if(singleTon == null){
                    singleTon = new SingleTon();
                }
            }
        }
        return singleTon;
    }
}