Lecture 3

In this lecture, we started describing how to implement a checkin application.

For next time:

Get the prototype code at: https://bitbucket.org/luca_de_alfaro/cmps121_clicker_portions .
Study a bit how getting the location works.
- Study a bit of the references below, especially Making Your App Location-Aware.

How to get the location

You need to add the <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> in the AndroidManifest.xml (or ACCESS_COARSE_LOCATION, but why would you ask for only that permission?).
- You need to include the Android Play services in your gradle file. You can either click, or add the line for gsm:play-services as below:

dependencies {

    compile fileTree(dir: 'libs', include: ['*.jar'])

    compile 'com.android.support:appcompat-v7:21.0.3'

    compile 'com.google.code.gson:gson:2.3.1'

    compile 'com.google.android.gms:play-services:7.0.0'

You need to register a location listener, like so:

        LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);

        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);

You need to write your own location listener

/**

     * Listenes to the location, and gets the most precise recent location.

*/

    LocationListener locationListener = new LocationListener() {

        @Override

        public void onLocationChanged(Location location) {

            // Do something with the location you receive.

        @Override

        public void onStatusChanged(String provider, int status, Bundle extras) {}

        @Override

        public void onProviderEnabled(String provider) {}

        @Override

        public void onProviderDisabled(String provider) {}

};

When you are done (e.g., in onPause), un-register the location update receiver, like so:

        // Stops the location updates.

        LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

        locationManager.removeUpdates(locationListener);

Location resources

Of course, we would all hope that all it takes is a call to OhGreatGoogle.gimmeLocation(howPreciseIneedIt); But by this point you hae already guessed it: if it looks trivial, then it's only a few dozen lines of code (and a few dozen pages of documentation). So here it goes:

A good page on Android location strategies
Android Location API : this is the main page, from there you can use the Places API if you want to find nearby Places (addresses, businesses, etc), or ...
You can read detailed instructions on how to get the lat/long location.
In particular, what we are doing in our app is documented here.

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