Android - Confirm app exit with toast

Question

I'm new to Android development and I want it so when the user presses the back button on the main activity, a toast message appears with a "confirm exit by pressing the back button again" message. How would I do this? This is what I have so far:

@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
    super.onBackPressed();
    Toast s = Toast.makeText(getBaseContext(), "Press back again to exit", Toast.LENGTH_LONG);
    s.show();
    wait();

    public boolean onBackPressed() {
        finish();    
    }
}

Kuska

Is the toast showing? What is/isn't working? It may be better to have a counter in there and if the counter = 2 then finish. Or use a dialog instead of a toast – Donato

Best solution in: #8431305 – Deoxyribose

Answer 1

I would just save the time of the backpress and then compare the time of the latest press to the new press.

long lastPress;
@Override
public void onBackPressed() {
    long currentTime = System.currentTimeMillis();
    if(currentTime - lastPress > 5000){
        Toast.makeText(getBaseContext(), "Press back again to exit", Toast.LENGTH_LONG).show();
        lastPress = currentTime;
    }else{
        super.onBackPressed();
    }
}

You can also dismiss the toast when the app the back press is confirmed (cred @ToolmakerSteve):

long lastPress;
Toast backpressToast;
@Override
public void onBackPressed() {
    long currentTime = System.currentTimeMillis();
    if(currentTime - lastPress > 5000){
        backpressToast = Toast.makeText(getBaseContext(), "Press back again to exit", Toast.LENGTH_LONG);
        backpressToast.show();
        lastPress = currentTime;
    } else {
        if (backpressToast != null) backpressToast.cancel();
        super.onBackPressed();
    }
}

Myrilla

Thank you, this is what I was wanting to do! With a toast rather than a dialogbox :) – Kuska

this is the proper solution for those who are wandering on many other topics! – Forefather

Also see user8218's enhancement of this, which removes the toast as soon as user presses back the second time: https://mcmap.net/q/87969/-android-confirm-app-exit-with-toast HOWEVER user8218's answer is WRONG as written; submitting a change that I explain in a comment on that; hopefully my change will be accepted. – Naoma

@Naoma updated my answer, please verify that it looks good. – Myrilla

Looks great! Thanks. (No need for people to look at user8218's answer now; this answer is complete. Thanks to user8218 for the idea. If you like that addition, consider upvoting that answer also.) – Naoma

An alternative answer to consider here. I haven't decided yet which approach I prefer. – Naoma

I have 2 remarks about this solution. First, the toast duration is 2000ms for LENGTH_SHORT and 3500ms for LENGTH_LONG. So maybe it would be better to use the corresponding value instead of 5000. The documentation says that this time could be user-definable. I couldn't find how to retrieve the actual value, which would have been better. Second, if you use a Drawer Menu for example, super.onBackPressed() will go back to the previous fragment and won't exit the app. So it's better to explicitly close the app with finish() instead of relying on super.onBackPressed(). – Juncture

Answer 2

private long mLastPress = 0;
const int TOAST_DURATION = 5000;
Toast onBackPressedToast;
@Override
public void onBackPressed() {
    long currentTime = System.currentTimeMillis();
    if (currentTime - mLastPress > TOAST_DURATION) {
        onBackPressedToast = Toast.makeText(this, R.string.press_once_again_to_exit, Toast.LENGTH_SHORT);
        onBackPressedToast.show();
        mLastPress = currentTime;
    } else {
        if (onBackPressedToast != null) {
            onBackPressedToast.cancel();  //Difference with previous answer. Prevent continuing showing toast after application exit.
            onBackPressedToast = null;
        }
        super.onBackPressed();
    }
}

Befall

In the previous answer the toast is only created on the first back press and that toast is not canceled in your answer. – Myrilla

[Submitted as an edit] Can fix this (per @Heinrisch' comment) by holding toast in a field outside the method: Toast onBackPressedToast; before the method. Then move onBackPressedToast = Toast... INSIDE the if. In the else, protect the cancel with if (onBackPressedToast != null). – Naoma

Also need const int TOAST_DURATION = 5000; – Naoma

... and might as well set toast variable to null, when we cancel it. – Naoma

@Naoma Why should we set the toast to null if the app will quit anyway? – Juncture

@Juncture - you are right, that is not necessary, given that we know the app is exiting. (Its a habit to clean up resources of variables outside of the method.) – Naoma

Answer 3

work perfectly in my case

private static long back_pressed;

@Override
public void onBackPressed()
{
        if (back_pressed + 2000 > System.currentTimeMillis()) 
               super.onBackPressed();
        else 
             Toast.makeText(getBaseContext(), "Press once again to exit!", Toast.LENGTH_SHORT).show();
        back_pressed = System.currentTimeMillis();
}

Zephyr

Please explain the differences from the most-upvoted answer that existed two years before this. What is different, and how is this an improvement over that answer? Also, what justifies making this a new answer, rather than a comment on that answer? (IMHO, it better serves future readers to suggest small changes in comments on an existing answer, rather than creating a whole new answer.) – Naoma

Answer 4

In newer version you can use the snackbar instead of toast.

import android.support.design.widget.Snackbar;
...
Snackbar.make(content, "Click BACK again to exit", Snackbar.LENGTH_SHORT).setAction("Action", null).show();
...

Scheffler

Answer 5

After having to implement the same behaviour many a times, decided to go aboiut building a library for the same : DoubleBackPress Android Library. It provides many easy to use templates and the double back press behaviour without all the hassle.

Just do :

// set the ToastDisplay to be shown on FirstBackPress
FirstBackPressAction firstBackPressAction = new ToastDisplay().standard(this);

// set the Action on DoubleBackPress
DoubleBackPressAction doubleBackPressAction = new DoubleBackPressAction() {
    @Override
    public void actionCall() {
        finish();
    }
};

// setup DoubleBackPress behaviour
DoubleBackPress doubleBackPress = new DoubleBackPress()
        .withDoublePressDuration(3000)
        .withFirstBackPressAction(firstBackPressAction)
        .withDoubleBackPressAction(doubleBackPressAction);

---

Finally, override the onBackPressed with DoubleBackPress behaviour for the back press.

@Override
public void onBackPressed() {
    doubleBackPress.onBackPressed();
}

Example GIF for similar behaviour

Livelihood

Answer 6

Best and simple solution with Toast

In Java

private Toast exitToast;

@Override
public void onBackPressed() {
    if (exitToast == null || exitToast.getView() == null || exitToast.getView().getWindowToken() == null) {
        exitToast = Toast.makeText(this, "Press again to exit", Toast.LENGTH_LONG);
        exitToast.show();
    } else {
        exitToast.cancel();
        finish();
    }
}

In Kotlin

private var exitToast: Toast? = null

override fun onBackPressed() {
    if (exitToast == null || exitToast!!.view == null || exitToast!!.view.windowToken == null) {
        exitToast = Toast.makeText(this, "Press again to exit", Toast.LENGTH_LONG)
        exitToast!!.show()
    } else {
        exitToast!!.cancel()
        finish()
    }
}

Morningglory