Android App series: Double-click the Back button to exit the program

Objective

There is a very old application skills, has been all kinds of large and small app used to be bored, that is, double-click the return key to exit the program. Writing its implementation code today is very simple and practical.

Body

Double-click the return key to exit the program, there are generally two implementation ideas, one is to use a Boolean variable to record the key event, and through the thread delay to achieve the effect; the other is directly through the record key time to calculate the timing of the implementation of the function, now share with you the Code bar, O (∩_∩) o haha ~

1, using thread delay to achieve

Private Static Booleanmbackkeypressed =false;//record If there is a first keystroke@Override Public voidonbackpressed () {if(!mbackkeypressed) {Toast.maketext ( This, "Press again to exit the program", Toast.length_short). Show (); Mbackkeypressed=true; NewTimer (). Schedule (NewTimerTask () {//delay two seconds, if out of the wrong first keystroke record 　　　　　　 @Override Public voidrun () {mbackkeypressed=false; }},2000); }Else{//Exit Program 　　　　  This. Finish (); System.exit (0); }}

Mbackkeypressed to record whether there is a record for the first press of the return key, if there is no first keystroke record, the toast prompt, and records the first keystroke record, and the startup thread erases the keystroke record after 2 seconds. If the online Chenghaine erase mbackkeypressed and press the back key, then the statement inside the else is executed to exit the program.

2, by calculating the time difference to achieve

Private LongMpressedtime = 0; @Override Public voidonbackpressed () {LongMnowtime = System.currenttimemillis ();//get the first keystroke time 　　 if((Mnowtime-mpressedtime) > 2000) {//compare two key time differenceToast.maketext ( This, "Press again to exit the program", Toast.length_short). Show (); Mpressedtime=Mnowtime; }Else{//Exit Program 　　　　  This. Finish (); System.exit (0); }}

This is accomplished by controlling the time difference, and when the return key is first pressed, the current period is assigned to Mpressedtime and the user is prompted by toast, and when the return key is pressed the second time, if the The Mpressedtime record has a time difference greater than 2 seconds to refresh the mpressedtime, and if less than 2 seconds the Else statement exits the program.

PS: It is recommended to use the time difference method to achieve this function, because the simple and stable code is much better than the thread delay.

If there is a better way to achieve, you are welcome to discuss the HA ~

Enjoy wind chimes
Source: http://www.cnblogs.com/net168/
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Android App series: Double-click the Back button to exit the program