giving a variable the value of one every 30 seconds

In android if a button is clicked i want a countdown to start from 30 and countdown to 0. I created a code with a basic countdown method but the problem is it doesn't continue to countdown if the activity or application closes.

What i want to do is for the activity or just the countdown to continue ticking down in the background until it hits 0 in which it'll change variable B to the value of 1.

I have expanded from my original model thinking i could compare dates times from when the button was clicked + 30 seconds to when the activity is called up upon again. But so fa开发者_运维技巧r i have come to a stump in comparing two datetimes in android.

Any help?

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What you likely want is an async task to run in the background. Something like:

private class JohnnysPollTask extends AsyncTask<Integer, Void, Integer> {
        /**
         * The system calls this to perform work in a worker thread and delivers
         * it the parameters given to AsyncTask.execute()
         */
        protected Integer doInBackground(Integer... millis) {
            try {
                int waited = 0;         
                                int duration = 30000;
                while (waited < duration) {
                    Thread.sleep(1000);
                    waited += 1000;

                    if (waited>=duration) {
                        b=1;
                        break;
                    }
                }
            } catch (InterruptedException e) {
                // do nothing
            }

            return 1;
        }

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Implement CountDownTimer

inside service.

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You could try using a service instead of an activity.