new Thread(new Runnable() {
    public void run() {
        someButton.post(new Runnable() {
            public void run() {
                while (HintergrundDienst.laeuft)
                {
                    //some delay code, like Thread.sleep
                }
                new Handler(Looper.getMainLooper()).post(new Runnable() {
                    @Override
                    public void run() {
                        //do on ui after HintergrundDienst.laeuft = false
                    }
                });
            }
        });
    }
}).start();