单例模式

https://blog.csdn.net/csdnliuxin123524/article/details/80032262

 

public class InnerSingleton {  
    private static class Singleton{  
        private static InnerSingleton single = new InnerSingleton();  
    }  
      
    public static InnerSingleton getInstance(){  
        return Singleton.single;  
    }  
}