Question

I follow this post What is the simplest and most robust way to get the user's current location on Android?

I have many questions about the post, but unfortunately I don’t have enough reputation to reply there, so I have to create a separate post. Sorry for any inconvenience.

Copy and past the code into my app and it works on my Samsung S2, but doesn’t work in the emulator (2.3).

My questions:

1. When run in the emulator, the code never reach the onLocationChanged() methods, instead it will wait for 20 sec (timeout set by the timer1) to start run() of GetLastLocation. Why?

2. Now, the run() method of GetLastLocation class is always called, and I got the exception above.

   (E/AndroidRuntime(436): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.).

I guess the error occurs in my code:

    public LocationResult locationResult = new LocationResult()
    {
        @Override
        public void gotLocation(final Location location)
        {
            Log.i(LOG_TAG, "gotLocation");
            if (location == null)
            {
                Log.i(LOG_TAG, "Cannot get location");
            }
            else
            {
                Log.i(LOG_TAG, "Lat: " + location.getLatitude() + " Long:" + location.getLongitude());
                tv = (TextView) findViewById(R.id.my_text); // <<< error here!!!
                            tv.setText(lat + "," + lon);
            }
        }
    };

TextView tv is initialized in my main Activity, which calls MyLocation myLocation = new MyLocation(); and myLocation.getLocation(this, locationResult);. The design is the same with that of the post. I wonder if the run() of GetLastLocation is called in another thread? Why is this? Has anyone got the same issue?

Thanks a lot!

Answer 1

When using an emulator, you need to set your current location to it. It can be done with a few different ways. Se them here. I think the simplest way to start testing is to use the telnet and geo commands.

As you can use findViewById I suppose you are in the inner class of some Activity. So, use the runOnUiThread method to update your views

runOnUiThread(new Runnable() {
    @Override
    public void run() {
        tv = (TextView) findViewById(R.id.my_text); 
        tv.setText(lat + "," + lon);
    }
});

In the sample code, location updates are received through a timer task, that’s why it is running in a separate thread.