android 再按一次后退键退出应用程序

方法一：
private static Boolean isExit = false;

    private static Boolean hasTask = false;

    Timer tExit = new Timer();

    TimerTask task = new TimerTask() {

         

        @Override

        public void run() {

            isExit = false;

            hasTask = true;

        }

    };

     

    @Override

    public boolean onKeyDown(int keyCode, KeyEvent event) {

        System.out.println("TabHost_Index.java onKeyDown");

        if (keyCode == KeyEvent.KEYCODE_BACK) {

            if(isExit == false ) {

                isExit = true;

                Toast.makeText(this, "再按一次后退键退出应用程序", Toast.LENGTH_SHORT).show();

                if(!hasTask) {

                    tExit.schedule(task, 2000);

                }

            } else {

                finish();

                System.exit(0);

            }

        }

        return false;

    }

方法2：

public class BackActivity extends Activity {



        private static final String TAG = "BackActivity";

        private long mLastBackTime = 0;

        private long TIME_DIFF = 2 * 1000;



        @Override

        public void onCreate(Bundle savedInstanceState) {

                super.onCreate(savedInstanceState);

                setContentView(R.layout.main);

        }



        @Override

        public boolean onKeyDown(int keyCode, KeyEvent event) {

                if (keyCode == KeyEvent.KEYCODE_BACK) {

                        long now = new Date().getTime();

                        if (now - mLastBackTime < TIME_DIFF) {

                                Log.d(TAG, "back, finish");

                                return super.onKeyDown(keyCode, event);

                        } else {

                                Log.d(TAG, "after 2s, toast");

                                mLastBackTime = now;

                                Toast.makeText(this, "再点一次将推出", 2000).show();

                        }

                        return true;

                }

                return super.onKeyDown(keyCode, event);

        }

}

 

建议用方法2

原文连接：http://gundumw100.iteye.com/blog/1561861