Using the Location Manager class, we can obtain periodic updates of the device's geographical locations as well as fire an intent when it enters the proximity of a certain location.
1. Obtain a reference to the LocationManager class using the getSystemService() method.
LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
2. Create a LocationListener Class for notify the location changes.
Our MyLocationListener class should implements the LocationListener abstract class. There are four methods that you need to override in this implementation:
* onLocationChanged(Location location): This method is called when the location has changed.
* onProviderDisabled(String provider): This method is called when the provider is disabled by the user.
* onProviderEnabled(String provider): This method is called when the provider is enabled by the user.
* onStatusChanged(String provider, int status, Bundle extras): This method is called when the provider status changes.
3. To be notified whenever there is a change in location, you need to register for a request for changes in locations so that your program can be notified periodically. This is done via the requestLocationUpdates() method (see Listing 1).
This method takes in four parameters:
* provider: The name of the provider with which you register
* minTime: The minimum time interval for notifications, in milliseconds.
* minDistance: The minimum distance interval for notifications, in meters.
* listener: An object whose onLocationChanged() method will be called for each location update.
4. Set the following User-Permission in androidmanifest.xml
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
Sample Code :
package com.cureent;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
public class TestActivity extends Activity implements OnClickListener, android.content.DialogInterface.OnClickListener {
private EditText editTextShowLocation;
private Button buttonGetLocation;
private ProgressBar progress;
private LocationManager locManager;
private LocationListener locListener = new MyLocationListener();
private boolean gps_enabled = false;
private boolean network_enabled = false;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
editTextShowLocation = (EditText) findViewById(R.id.editText1);
progress = (ProgressBar) findViewById(R.id.progressBar1);
progress.setVisibility(View.GONE);
buttonGetLocation = (Button) findViewById(R.id.button1);
buttonGetLocation.setOnClickListener(this);
locManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
}
@Override
public void onClick(View v) {
progress.setVisibility(View.VISIBLE);
// exceptions will be thrown if provider is not permitted.
try {
gps_enabled = locManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
} catch (Exception ex) {
}
try {
network_enabled = locManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
} catch (Exception ex) {
}
// don't start listeners if no provider is enabled
if (!gps_enabled && !network_enabled) {
AlertDialog.Builder builder = new Builder(this);
builder.setTitle("Attention!");
builder.setMessage("Sorry, location is not determined. Please enable location providers");
builder.setPositiveButton("OK", this);
builder.setNeutralButton("Cancel", this);
builder.create().show();
progress.setVisibility(View.GONE);
}
if (gps_enabled) {
locManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locListener);
}
if (network_enabled) {
locManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locListener);
}
}
class MyLocationListener implements LocationListener {
@Override
public void onLocationChanged(Location location) {
if (location != null) {
// This needs to stop getting the location data and save the battery power.
locManager.removeUpdates(locListener);
String londitude = "Londitude: " + location.getLongitude();
String latitude = "Latitude: " + location.getLatitude();
String altitiude = "Altitiude: " + location.getAltitude();
String accuracy = "Accuracy: " + location.getAccuracy();
String time = "Time: " + location.getTime();
editTextShowLocation.setText(londitude + "\n" + latitude + "\n" + altitiude + "\n" + accuracy + "\n" + time);
progress.setVisibility(View.GONE);
}
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
@Override
public void onClick(DialogInterface dialog, int which) {
if(which == DialogInterface.BUTTON_NEUTRAL){
editTextShowLocation.setText("Sorry, location is not determined. To fix this please enable location providers");
}else if (which == DialogInterface.BUTTON_POSITIVE) {
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
}
}
Reverse geocoding:
package com.exercise.AndroidFromLocation;
import java.io.IOException;
import java.util.List;
import java.util.Locale;
import android.app.Activity;
import android.location.Address;
import android.location.Geocoder;
import android.os.Bundle;
import android.widget.TextView;
public class AndroidFromLocation extends Activity {
double LATITUDE = 37.42233;
double LONGITUDE = -122.083;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TextView myLatitude = (TextView)findViewById(R.id.mylatitude);
TextView myLongitude = (TextView)findViewById(R.id.mylongitude);
TextView myAddress = (TextView)findViewById(R.id.myaddress);
myLatitude.setText("Latitude: " + String.valueOf(LATITUDE));
myLongitude.setText("Longitude: " + String.valueOf(LONGITUDE));
Geocoder geocoder = new Geocoder(this, Locale.ENGLISH);
try {
List<Address> addresses = geocoder.getFromLocation(LATITUDE, LONGITUDE, 1);
if(addresses != null) {
Address returnedAddress = addresses.get(0);
StringBuilder strReturnedAddress = new StringBuilder("Address:\n");
for(int i=0; i<returnedAddress.getMaxAddressLineIndex(); i++) {
strReturnedAddress.append(returnedAddress.getAddressLine(i)).append("\n");
}
myAddress.setText(strReturnedAddress.toString());
}
else{
myAddress.setText("No Address returned!");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
myAddress.setText("Canont get Address!");
}
}
}
Main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Location"
android:background="#505050"
/>
<TextView
android:id="@+id/mylatitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="@+id/mylongitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Address"
android:background="#505050"
/>
<TextView
android:id="@+id/myaddress"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
