Android“再按一次退出程序”实现

为了降低用户误操作退出程序的概率，很多应用都会采用“再按一次退出程序”的方式来处理。实现原理下图所示：

实现方式如下：

private long exitTime = 0;@Override    public void onBackPressed() {        if ((System.currentTimeMillis() - exitTime) > 2000) {            Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();            exitTime = System.currentTimeMillis();        } else {            System.exit(0);        }    }

退出程序的实现

public class MyApplication extends Application{    public Context appContext = null;    private List mList = new LinkedList();    private static MyApplication instance;    public MyApplication() {    }    @Override    public void onCreate() {        super.onCreate();        appContext = getApplicationContext();    }    public synchronized static MyApplication getInstance() {        if (null == instance) {            instance = new MyApplication();        }        return instance;    }    public void addActivity(Activity activity) {        mList.add(activity);    }    public void exit() {        try {            for (Activity activity : mList) {                if (activity != null)                    activity.finish();            }        } catch (Exception e) {            e.printStackTrace();        } finally {            System.exit(0);        }    }    public void onLowMemory() {        super.onLowMemory();        System.gc();    }}

创建一个BaseActivity，所有的Activity都继承自自BaseActivity

public class BaseActivity extends Activity {    private BaseActivity oContext;    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        oContext = this;// 把当前的上下文对象赋值给BaseActivity        MyApplication.getInstance().addActivity(this);    }}

在需要退出程序的地方调用，即可退出程序

MyApplication.getInstance().exit();

退出程序的实现

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