Sensor Fun: Location Based Services and GPS for Android

May 30th, 2010 by Micha Kops

The Android SDK offers a nice API to receive information about available providers for location based services and get the current location and coordinates.

In this short tutorial we’re going to build a small activity that displays a list of available location providers and shows the current position using GPS services.

Example Application
Screenshots
Converting to a Maven Project
Resources
Article Updates

Example Application

Create a new Android Project using ADT and your IDE with a package named com.hascode.android.location_app

Add the permissions needed to the AndroidManifest.xml – it should look like this

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
	package="com.hascode.android.location_app" android:versionCode="1"
	android:versionName="1.0">
	<application android:icon="@drawable/icon" android:label="@string/app_name">
		<activity android:name=".LocationActivity" android:label="@string/app_name">
			<intent-filter>
				<action android:name="android.intent.action.MAIN" />
				<category android:name="android.intent.category.LAUNCHER" />
			</intent-filter>
		</activity>
 
	</application>
	<uses-sdk android:minSdkVersion="7" />
 
	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION"></uses-permission>
</manifest>

Create a layout with one text view and two buttons in the main.xml

<?xml version="1.0" encoding="utf-8"?>
<TableLayout android:layout_width="fill_parent"
	android:layout_height="fill_parent" android:orientation="vertical"
	xmlns:android="http://schemas.android.com/apk/res/android">
	<TextView android:id="@+id/output" android:layout_width="wrap_content"
		android:layout_height="wrap_content" android:text="@string/loading">
	</TextView>
	<Button android:id="@+id/btShowProviders" android:layout_width="wrap_content"
		android:layout_height="wrap_content" android:text="@string/showProviders">
	</Button>
	<Button android:id="@+id/btShowLocation" android:layout_width="wrap_content"
		android:layout_height="wrap_content" android:text="@string/showLocation">
	</Button>
</TableLayout>

Externalize the strings in the strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <string name="app_name">LocationApp</string>
 <string name="loading">loading...</string>
 <string name="showProviders">Show available providers</string>
 <string name="showLocation">Listen to coordinate updates</string>
</resources>

Create the activity LocationActivity

package com.hascode.android.location_app;
 
import java.util.List;
 
import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
 
public class LocationActivity extends Activity implements LocationListener {
	// attrs
	private static final String TAG = "com.hascode.android.location-app";
	private LocationManager locationManager;
	private static final String PROVIDER = "gps"; // for this tutorial we simply
	// assume that this provider
	// exists
 
	// ui elements
	private TextView output;
	private Button btShowProviders;
	private Button btShowLocation;
 
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
 
		output = (TextView) findViewById(R.id.output);
		btShowProviders = (Button) findViewById(R.id.btShowProviders);
		btShowLocation = (Button) findViewById(R.id.btShowLocation);
 
		locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
		if (locationManager == null) {
			Log.w(TAG, "no location manager found");
			output.setText("no location manager no fun ..");
		} else {
			btShowProviders.setOnClickListener(new View.OnClickListener() {
				@Override
				public void onClick(View view) {
					showProviders();
				}
			});
 
			btShowLocation.setOnClickListener(new View.OnClickListener() {
				@Override
				public void onClick(View view) {
					showLocation();
				}
			});
		}
	}
 
	/**
	 * shows the list of available location providers
	 */
	private void showProviders() {
		List<String> providers = locationManager.getAllProviders();
		Log.d(TAG, "available providers found: " + providers.size());
		StringBuilder s = new StringBuilder();
		for (String provider : providers) {
			s.append(provider);
			s.append("\n");
		}
		output.setText(s.toString());
	}
 
	/**
	 * displays the current location using the gps provider
	 */
	private void showLocation() {
		LocationProvider gps = locationManager.getProvider(PROVIDER);
		if (gps == null) {
			Log.w(TAG, "gps provider not found");
			return;
		}
 
		locationManager.requestLocationUpdates(PROVIDER, 1200, 5, this);
		Log.d(TAG, "listening to gps events started");
	}
 
	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * android.location.LocationListener#onLocationChanged(android.location.
	 * Location)
	 */
	@Override
	public void onLocationChanged(Location location) {
		String result = String.format(
				"Your coords: latitude %f is longitude is %f", location
						.getLatitude(), location.getLongitude());
		Log.d(TAG, "location update received: " + result);
		output.setText(result);
	}
 
	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * android.location.LocationListener#onProviderDisabled(java.lang.String)
	 */
	@Override
	public void onProviderDisabled(String provider) {
		Log.d(TAG, "the following provider was disabled: " + provider);
	}
 
	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * android.location.LocationListener#onProviderEnabled(java.lang.String)
	 */
	@Override
	public void onProviderEnabled(String provider) {
		Log.d(TAG, "the following provider was enabled: " + provider);
	}
 
	/*
	 * (non-Javadoc)
	 *
	 * @see android.location.LocationListener#onStatusChanged(java.lang.String,
	 * int, android.os.Bundle)
	 */
	@Override
	public void onStatusChanged(String provider, int status, Bundle extras) {
		Log.d(TAG, String.format(
				"Provider status has changed. provider: %s, status: %d",
				provider, status));
	}
}

Run the app on your emulator and use ddms or the emulator control view if you’re using eclipse like me

Screenshots

Converting to a Maven Project

If you want to use Maven with your project, take a look at this article – my pom.xml looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <groupId>com.hascode.android.location_app</groupId>
 <artifactId>location-app</artifactId>
 <packaging>apk</packaging>
 <name>hasCode.com - Sample Location App</name>
 <version>0.1</version>
    <dependencies>
        <dependency>
            <groupId>android</groupId>
            <artifactId>android</artifactId>
            <version>2.1_r1</version>
           <scope>provided</scope>
        </dependency>
    </dependencies>
 
    <build>
        <sourceDirectory>src</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>com.jayway.maven.plugins.android.generation2</groupId>
                <artifactId>maven-android-plugin</artifactId>
                <configuration>
                    <sdk>
                        <path>${env.ANDROID_HOME}</path>
                        <platform>1.6</platform>
                    </sdk>
                    <deleteConflictingFiles>true</deleteConflictingFiles>
                </configuration>
                <extensions>true</extensions>
            </plugin>
        </plugins>
    </build>
 </project>

Logging and Filtering

Take a look at the logs using the adb tool and filter for entries with the tag “com.hascode.android.location-app“:

adb -s emulator-5554 shell
# logcat com.hascode.android.location-app:D *:S
D/com.hascode.android.location-app(  209): available providers found: 1
D/com.hascode.android.location-app(  209): listening to gps events started
D/com.hascode.android.location-app(  209): listening to gps events started
D/com.hascode.android.location-app(  209): available providers found: 1
D/com.hascode.android.location-app(  209): listening to gps events started

Resources

Article Updates

2015-03-03: Table of contents added.

package com.hascode.android.location_app;

import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class LocationActivity extends Activity implements LocationListener {
// attrs
private static final String TAG = “com.hascode.android.location-app”;
private LocationManager locationManager;
private static final String PROVIDER = “gps”; // for this tutorial we simply
// assume that this provider
// exists

// ui elements
private TextView output;
private Button btShowProviders;
private Button btShowLocation;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

output = (TextView) findViewById(R.id.output);
btShowProviders = (Button) findViewById(R.id.btShowProviders);
btShowLocation = (Button) findViewById(R.id.btShowLocation);

locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if (locationManager == null) {
Log.w(TAG, “no location manager found”);
output.setText(“no location manager no fun ..”);
} else {
btShowProviders.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showProviders();
}
});

btShowLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showLocation();
}
});
}
}

/**
* shows the list of available location providers
*/
private void showProviders() {
List<String> providers = locationManager.getAllProviders();
Log.d(TAG, “available providers found: ” + providers.size());
StringBuilder s = new StringBuilder();
for (String provider : providers) {
s.append(provider);
s.append(“\n”);
}
output.setText(s.toString());
}

/**
* displays the current location using the gps provider
*/
private void showLocation() {
LocationProvider gps = locationManager.getProvider(PROVIDER);
if (gps == null) {
Log.w(TAG, “gps provider not found”);
return;
}

locationManager.requestLocationUpdates(PROVIDER, 1200, 5, this);
Log.d(TAG, “listening to gps events started”);
}

/*
* (non-Javadoc)
*
* @see
* android.location.LocationListener#onLocationChanged(android.location.
* Location)
*/
@Override
public void onLocationChanged(Location location) {
String result = String.format(
“Your coords: latitude %f is longitude is %f”, location
.getLatitude(), location.getLongitude());
Log.d(TAG, “location update received: ” + result);
output.setText(result);
}

/*
* (non-Javadoc)
*
* @see
* android.location.LocationListener#onProviderDisabled(java.lang.String)
*/
@Override
public void onProviderDisabled(String provider) {
Log.d(TAG, “the following provider was disabled: ” + provider);
}

/*
* (non-Javadoc)
*
* @see
* android.location.LocationListener#onProviderEnabled(java.lang.String)
*/
@Override
public void onProviderEnabled(String provider) {
Log.d(TAG, “the following provider was enabled: ” + provider);
}

/*
* (non-Javadoc)
*
* @see android.location.LocationListener#onStatusChanged(java.lang.String,
* int, android.os.Bundle)
*/
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
Log.d(TAG, String.format(
“Provider status has changed. provider: %s, status: %d”,
provider, status));
}
}

Tags: activity, adt, Android, example, gps, lbs, location, mobile, sample, tutorial

This entry was posted on Sunday, May 30th, 2010 at 2:14 pm and is filed under Android. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

2 Responses to “Sensor Fun: Location Based Services and GPS for Android”

john hewitt Says:
August 24th, 2010 at 1:00 pm
thanks for the tutorial. I have one problem when i try to run. I have error x’s in the location activity and when I run I get this error: An internal error occurred during: “Launching New_configuration”. Path for project must have only one segment.

thanks for any advice,

john
steven Says:
August 24th, 2010 at 7:52 pm
Hi John,

whats your environment? Are you using Eclipse with installed Android SDK? And running the application using Run as .. Android Application?

greets

steven