Question

I have created my own class that extends CountDownTimer. Since I use it often, I would like to have that class in its own java file.

However, I do not know of a way for the timer class to communicate with the class that created it.

Example: class A has a textView that displays some number of seconds. So, class A creates the timer.

• How can the onTick() method in CountDownTimer be told to update my
  textView with the current time?
• How can my class A know when the timer has finished?

I’m sure it’s a simple answer, I just know very little about threads, handlers, listeners, and whatever else you wizards are cooking up.

Answer 1

This should be very similar using a regular countdown timer – just substitute your subclass for the regular timer instance. Also, pass the activity into the constructor so it can do whatever it needs to update the display.

E.g.

    mCountDownTimer = MyCountDownTimer(totalMsecs, callInterval, this).start();

Where MyCountownTime would have methods like this:

        public void onTick(long millisUntilFinished) {

            float fraction = millisUntilFinished / (float) totalMsecs;

                        // myActivity is passed in the constructor
            mMillisUntilFinished = millisUntilFinished;

            // progress bar is based on scale of 1 to 100;
            mActivity.progressBar.setProgress((int) (fraction * 100));

        }

        public void onFinish() {
                mMillisUntilFinished = 0;
            handleTimeOut();
        }

This assumes mActivity is passed in the constructor. I changed the code to assume the calling activity was passed as a variable in the timer constructor and set as a member of the timer class.