Answers for "how to show a toast in android continuosly without break when the app is put in background"

toast.maketext

Context context = getApplicationContext();
CharSequence text = "Hello toast!";
int duration = Toast.LENGTH_SHORT;

Toast toast = Toast.makeText(context, text, duration);
toast.show();

android java toast

Toast.makeText(this, "Mmm Toasty", Toast.LENGTH_LONG).show();