Android: Proper Way to use onBackPressed() with Toast

I would implement a dialog asking the user if they wanted to exit and then call super.onBackPressed() if they did.

@Override
public void onBackPressed() {
    new AlertDialog.Builder(this)
        .setTitle("Really Exit?")
        .setMessage("Are you sure you want to exit?")
        .setNegativeButton(android.R.string.no, null)
        .setPositiveButton(android.R.string.yes, new OnClickListener() {

            public void onClick(DialogInterface arg0, int arg1) {
                WelcomeActivity.super.onBackPressed();
            }
        }).create().show();
}

In the above example, you'll need to replace WelcomeActivity with the name of your activity.

You don't need a counter for back presses.

Just store a reference to the toast that is shown:

private Toast backtoast;

Then,

public void onBackPressed() {
    if(USER_IS_GOING_TO_EXIT) {
        if(backtoast!=null&&backtoast.getView().getWindowToken()!=null) {
            finish();
        } else {
            backtoast = Toast.makeText(this, "Press back to exit", Toast.LENGTH_SHORT);
            backtoast.show();
        }
    } else {
        //other stuff...
        super.onBackPressed();
    }
}

This will call finish() if you press back while the toast is still visible, and only if the back press would result in exiting the application.