Using toast inside timertask

Question

Found someone has similar issue online here.

This doesn't work:

Timer t = new Timer(false);
t.schedule(new TimerTask() {
@Override
public void run() {
Toast.makeText(getApplicationContext(), "msg", Toast.LENGTH_LONG).show();
}
}, 5000);

But if I instantiate the toast outside the timertask then show it inside run,it works.

I think it may relate to the so-called UI thread,

but how exactly ?

Answer 1

try this

Timer t = new Timer(false);
t.schedule(new TimerTask() {
@Override
public void run() {
       runOnUiThread(new Runnable() {
            public void run() {
                Toast.makeText(getApplicationContext(), "msg", Toast.LENGTH_LONG).show();
            }
        });

    }
}, 5000);

Answer 2

Using Timer starts a new thread, I suppose that thread does not have access to getApplicationContext. The proper way to do it is to use Handler and call the postDelayed method of the Handler - which does not start a new thread.

Read about this: http://developer.android.com/resources/articles/timed-ui-updates.html

The link you posted has a working example, which is the proper way to do it:

final Context ctx = this;
Handler mHandler = new Handler();

Runnable
makeToast = new Runnable() {
    public void run() {
        Toast.makeText(ctx, "msg", Toast.LENGTH_LONG).show();
    }
};
mHandler.postDelayed(makeToast, 1000);