How to quit android application programmatically

Question

I Found some codes for quit an Android application programatically. By calling any one of the following code in onDestroy() will it quit application entirely?

Answer 1

finishAffinity();

System.exit(0);

If you will use only finishAffinity(); without System.exit(0); your application will quit but the allocated memory will still be in use by your phone, so... if you want a clean and really quit of an app, use both of them.

This is the simplest method and works anywhere, quit the app for real, you can have a lot of activity opened will still quitting all with no problem.

example on a button click

public void exitAppCLICK (View view) {

    finishAffinity();
    System.exit(0);

}

or if you want something nice, example with an alert dialog with 3 buttons YES NO and CANCEL

// alertdialog for exit the app
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);

// set the title of the Alert Dialog
alertDialogBuilder.setTitle("your title");

// set dialog message
alertDialogBuilder
        .setMessage("your message")
        .setCancelable(false)
        .setPositiveButton("YES"),
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog,
                                        int id) {
                        // what to do if YES is tapped
                        finishAffinity();
                        System.exit(0);
                    }
                })

        .setNeutralButton("CANCEL"),
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog,
                                        int id) {
                        // code to do on CANCEL tapped
                        dialog.cancel();
                    }
                })

        .setNegativeButton("NO"),
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog,
                                        int id) {
                        // code to do on NO tapped
                        dialog.cancel();
                    }
                });

AlertDialog alertDialog = alertDialogBuilder.create();

alertDialog.show();