Display Alert Dialog on Back button Pressed in Android

How to Exit With an Alert Dialog Using back button in Android

    @Override
    public void onBackPressed() {
              
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setCancelable(false);
        builder.setMessage("Do you want to Exit?");
        builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
              //if user select "Yes", app will exit
              Intent intent = new Intent(Intent.ACTION_MAIN);
              intent.addCategory(Intent.CATEGORY_HOME);
              intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
              startActivity(intent);
              finish();
              System.exit(0);


               
               
            }
        });
        builder.setNegativeButton("No",new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                //if user select "No", just cancel this dialog and continue with app
                dialog.cancel();
            }
        });
        AlertDialog alert=builder.create();
        alert.show();
    }