Measure elapsed time between two MotionEvents in Android

问题

I'm new in Android programming so I am asking for your help in my problem. I am trying to measure in seconds/milliseconds the amount of time between a MouseEvent.ACTION_DOWN and MouseEvent.ACTION_UP.

@Override
public boolean onTouchEvent(MotionEvent event) {
    long start=0;
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        // manage down press
        start=System.nanoTime();//START
        System.out.println("START");
    }
    else if (event.getAction() == MotionEvent.ACTION_MOVE) {
        // manage move
        System.out.println(event.getRawX()+","+event.getRawY());
    }
    else {
        // manage up
        long finish=System.nanoTime()//FINISH
        long seconds = (finish-start) / 1000000000;//for seconds
        Toast.makeText(this, "FINISH, duration: "+seconds, Toast.LENGTH_SHORT).show();
        System.out.println("FINISH, duration: "+seconds);
    }
    return true;
}




Logcat:
03-19 04:04:27.140: I/System.out(4348): START
03-19 04:04:27.160: I/System.out(4348): 517.0,280.0
03-19 04:04:27.190: I/System.out(4348): 517.0,280.0
03-19 04:04:27.200: I/System.out(4348): 517.0,280.0
03-19 04:04:27.220: I/System.out(4348): 517.0,280.0
03-19 04:04:27.250: I/System.out(4348): 517.0,280.0
03-19 04:04:27.260: I/System.out(4348): 517.0,280.0
03-19 04:04:27.300: I/System.out(4348): 517.0,280.0
03-19 04:04:27.310: I/System.out(4348): 517.0,280.0
03-19 04:04:27.330: I/System.out(4348): FINISH, duration: 16545

My problem consist in fact that seconds variable doesn't show what I want, I even don't know if its measuring correctly.For the above example duration was 16545 (???!?!?) but it should have been between 1-3 seconds.What shall I do to measure correctly in seconds or milliseconds the time between two MotionEvents or what am I wrong in my example ? Thank you !

回答1:

long startTime;
public boolean onTouchEvent(MotionEvent event) {

    if (event.getAction() == MotionEvent.ACTION_DOWN) 
        startTime = System.nanoTime();    

    else if (event.getAction() == MotionEvent.ACTION_UP) {
        long elapseTime = System.nanoTime() - startTime;
        //do whatever u want with elapseTime now, its in nanoseconds
    }
}

回答2:

A MotionEvent has a timestamp. Use getEventTime() to access it.

In fact, since there is no guarantee that the MotionEvent is delivered immediately to your code, this timestamp is more accurate than any times you get from System.getCurrentTimeMillis().

回答3:

Here is the solution described by @CvR:

private long startTimeInMilliSec;
@Override 
public boolean onTouchEvent(MotionEvent event) {

    if (event.getAction() == MotionEvent.ACTION_DOWN) 
        startTimeInMilliSec = event.getEventTime();    

    else if (event.getAction() == MotionEvent.ACTION_UP) {
        long elapsedTime = event.getEventTime() - startTimeInMilliSec;
        //do whatever u want with elapsedTime now, its in milliseconds 
    } 
}