Android "Press again to quit program" specific implementation

Many of the ways to quit programs in Android apps are when you click on the Back button, it pops up a message "press again to exit", this and when we just need to press the Back button, the program exits, sometimes the time interval is 3 seconds or other time interval, today I will briefly say the implementation principle.

In fact, the implementation is relatively simple, we need to cover a method in the activity: public void onbackpressed (); This method is called when the return key is clicked, overwriting this method after we rewrite its implementation:

<span style= "White-space:pre" ></span>private static long back_pressed = 0; @Overridepublic void Onbackpressed () {if (Back_pressed+2000>system.currenttimemillis ()) super.onbackpressed (); else {Toast.makeText ( This, "Press again to Exit", "()" Show (); back_pressed = System.currenttimemillis ();}}

We also need to define a static variable as shown in the code to record the time we clicked the button, from the code we can know, when we click on the button, we first determine whether the current back_pressed+2000 value is greater than the current system time, if greater than, then we exit the program, If not greater than, that is, after we clicked the return button, in the interval of 2 seconds we did not click the second time, so the program does not exit, but record the time of the click, for the next click to make a judgment preparation.

Android "Press again to quit program" specific implementation