Android實現兩次按下返回鍵退出

標籤：

1. @Override  
2.     public boolean onKeyDown(int keyCode, KeyEvent event)   
3.     {  
4.                  if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN)  
5.                  {  
6.                            
7.                          if((System.currentTimeMillis()-exitTime) > 2000)  //System.currentTimeMillis()不管何時調用，肯定大於2000  
8.                          {  
9.                           Toast.makeText(getApplicationContext(), "再按一次退出程式",Toast.LENGTH_SHORT).show();                                  
10.                           exitTime = System.currentTimeMillis();  
11.                          }  
12.                          else  
13.                          {  
14.                              finish();  
15.                              System.exit(0);  
16.                          }  
17.                                    
18.                          return true;  
19.                  }  
20.                  return super.onKeyDown(keyCode, event);  
21.     }  

Android實現兩次按下返回鍵退出