How to get data from thread to activity in android

Here is my Thread

public class ReadPaycardThread implements Runnable {

    String applicationLabel = null; 
}

I want to use this variable value in the activity.

Runnable isn't a Thread, it's just a "piece of code to execute" but it could be executed in any Thread.

class MainActivity extends Activity {
    Handler mMainHandler;
    public onCreate(..) {
        mMainHandler = new Handler(Looper.getMainLooper()) {
            @UiThread @MainThread
            public void handleMessage(Message message) {
                switch (message.what) {
                    case 1234: {
                        final String cApplicationLabel = (String)message.obj;
                        //YOU CAN USE THIS STRING IN ANY PLACE OF MainActivity like "TextView.setText(cApplicationLabel)"
                        break;
                    }
                }
            }
        }
    }
    @AnyThread
    public boolean sendToActivity() {
        if (mMainHandler == null) return false;
        final String cApplicationLabel = "TEST LABEL";
        return mMainHandler.sendMessage(Message.obtain(mMainHandler, 1234, cApplicationLabel));
    }
}

You can call "sendToActivity()" from everywhere you "see" it, and it will delivers a String to MainActivity