Android 开发笔记——全局变量

Android全局变量的经典实现：使用继承自Application的自定义类，通过getApplicationContext()方法获取子类并获取系统变量，感觉有点类似ASP.NET中的Application。 

class MyApp extends Application {  
  
  private User user;  
  
  public User getUser(){  
    return user;  
  }  
  public void setState(User u){  
    user=u;  
  }  
}  

调用

class ActivityDemo extends Activity {  
  
  @Override  
  public void onCreate(Bundle savedInstanceState){  
     
    MyApp appState = ((MyApp)getApplicationContext());  
    User user= appState.getUser();  
    
  }