java - create simple timer android -

i want make simple timer time how long takes user in app. have in mind start timer, stop timer , display time. have been searching , haven't found definitive solution works. simple envision or more complicated have found searching?

how precise timer need be?

the simplest way take time before performing task , subtract time after performing task:

long start = system.currenttimemillis(); // task long timetakenms = system.currenttimemillis() - start; 

if mean user-event-driven timer, can apply same principles above:

// declare instance variable long start = 0l;  // onstarttimer start = system.currenttimemillis();  // onstoptimer long elapsed = system.currenttimemillis() - start;