Android Verification Code Countdown implementation

Android provides a convenient class Android.os.CountDownTimer for the verification Code countdown

How to use it:

New Countdowntimer (30000, +) {     publicvoid OnTick (long  millisuntilfinished) {          mtextfield.settext ("seconds remaining:" + millisuntilfinished/1000);     }      publicvoid  onfinish () {         mtextfield.settext ("done!" );      }  }. Start ();

OnTick Interval callback onfinish Countdown end Callback

From the source can see its implementation is mainly through the sendmessagedelayed implementation, its main logic is as follows:

PrivateHandler Mhandler =NewHandler () {@Override Public voidhandlemessage (Message msg) {synchronized(Countdowntimer. This) {                if(mcancelled) {return; }                Final LongMillisleft = Mstoptimeinfuture-Systemclock.elapsedrealtime (); if(Millisleft <= 0) {onfinish (); } Else if(Millisleft <mcountdowninterval) {                    //no tick, just delay until donesendmessagedelayed (Obtainmessage (MSG), millisleft); } Else {                    LongLasttickstart =Systemclock.elapsedrealtime ();                    OnTick (Millisleft); //Take into account user's OnTick taking time to execute                    LongDelay = Lasttickstart + Mcountdowninterval-Systemclock.elapsedrealtime (); //Special Case:user ' s OnTick took more than interval to//Complete , skip to next interval                     while(Delay < 0) Delay + =Mcountdowninterval;                Sendmessagedelayed (Obtainmessage (MSG), delay); }            }        }    };

It is possible to do some related logic at a later time by doing some timed operations.

Android Verification Code Countdown implementation