线程安全单例模式和context的标准用法

前言：当你感到不舒服的时候就是成长的时候

public class MySingleton {  
      
    //内部类  
    private static class MySingletonHandler{  
        private static MySingleton instance = new MySingleton();  
    }   
      
    private MySingleton(){}  
       
    public static MySingleton getInstance() {   
        return MySingletonHandler.instance;  
    }  
}  

public class MyApplication extends Application {  
      
    private static MyApplication app;  
      
    public static MyApplication getInstance() {  
        return app;  
    }  
      
    @Override  
    public void onCreate() {  
        super.onCreate();  
        app = this;  
    }  
      
}