每次我运行Android应用程式时当机

Question

I started BLE113 and Android programming. I followed the guidelines from this website:

http://www.software7.com/blog/creating-a-beacon-app-for-android-in-less-than-10-minutes-from-scratch/

Everything was working great when I followed the tutorial. Then I started to play with the code. Instead of reading the distance and the UUID on the Android terminal, I decided to read it on the app. The app is being shutdown each time I run it and getting the following message: “unfortunately, app name has stopped”. I really don't understand why is that. Here is the code when my app crashes:

public void didRangeBeaconsInRegion(Collection<Beacon> beacons, org.altbeacon.beacon.Region region) {
    for (Beacon oneBeacon: beacons) {
       // Log.d(Tag, "distance:"+oneBeacon.getDistance() + "id:" +oneBeacon.getId1()+ "/" + oneBeacon.getId2()+"/" + oneBeacon.getId3());

        TextView distance = (TextView) findViewById(R.id.distanceText);
        distance.setText(""+oneBeacon.getDistance());

    }
}

Here is when it doesn't crash:

public void didRangeBeaconsInRegion(Collection<Beacon> beacons, org.altbeacon.beacon.Region region) {
    for (Beacon oneBeacon: beacons) {
       Log.d(Tag, "distance:"+oneBeacon.getDistance() + "id:" +oneBeacon.getId1()+ "/" + oneBeacon.getId2()+"/" + oneBeacon.getId3());

        //TextView distance = (TextView) findViewById(R.id.distanceText);
        //distance.setText(""+oneBeacon.getDistance());

    }
}

Full code is published here:

https://github.com/Boniface316/androidProjects#androidprojects

I started Android programming 4 weeks ago and still learning, I really don't know why I am getting this message. Any suggestions or feedback is greatly appreciated.

Answer 1

You should always use the debugging tools to get errors using eclipse or Android Studio. That is the best way to find the issue

As far as I can see you should remove the initialization of distance out this method.

Declare it as a field:

private TextView distance;

intialize it in onCreate()

distance = (TextView) findViewById(R.id.distanceText);

Then

public void didRangeBeaconsInRegion(Collection<Beacon> beacons, org.altbeacon.beacon.Region region) {
    for (Beacon oneBeacon: beacons) {
       // Log.d(Tag, "distance:"+oneBeacon.getDistance() + "id:" +oneBeacon.getId1()+ "/" + oneBeacon.getId2()+"/" + oneBeacon.getId3());
        distance.setText(distance.getText() +  " | "+oneBeacon.getDistance());
    }
}

Also change the loop code to :

distance.setText(distance.getText() +  " | "+oneBeacon.getDistance());

Otherwise you would overwrite it

Answer 2

I don't know about the beacon thing... but as I guess,

that didRangeBeaconsInRegion method is being called from another thread, which is not main UI thread.

In android, UI related works are needed to be done in main thread and network related works have to be done in a separate thread.

I guess that beacon thing uses the network connection in another thread and calls this method in its own network thread.

Try using handler to send message to main thread for UI update.