How to toast a message when an user come into a particular area in googlemaps

Issue

the fixed location's latitude and longitude are (13.060422000000000000,80.249583000000030000). if my device is with in 20m of that location, it has to show the message like you in the area. if going out, it should show you are going out of place. For now i have created a map and getting the user's location and displaying. But i do not know how to do this. Please help me to do this. My code is MainActivity.java

public class MainActivity extends Activity implements LocationListener{
    // static final LatLng TutorialsPoint = new LatLng(13.060422000000000000,
    // 80.249583000000030000);
    private GoogleMap googleMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        try {
            if (googleMap == null) {
                googleMap = ((MapFragment) getFragmentManager()
                        .findFragmentById(R.id.map)).getMap();
            }
            //googleMap.setMyLocationEnabled(true);
            googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

            LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE);
            Criteria criteria = new Criteria();
            String provider = service.getBestProvider(criteria, false);

            Location location = service.getLastKnownLocation(provider);
            LatLng userLocation = new LatLng(location.getLatitude(),
                    location.getLongitude());
            googleMap.addMarker(new MarkerOptions().position(userLocation)
                    .title("Adaptavant Technologies"));

            googleMap.moveCamera(CameraUpdateFactory.newLatLng(userLocation));

            googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));
            CircleOptions options=new CircleOptions().center(userLocation).radius(20).fillColor(0x400099FF).strokeColor(Color.TRANSPARENT).strokeWidth(2);
            googleMap.addCircle(options);

        } catch (Exception e) {
            Log.e("simon", "Error : " + e.getMessage());
            e.printStackTrace();
        }
    }

    @Override
    public void onLocationChanged(Location arg0) {
        Toast.makeText(getApplicationContext(), "You are moving", Toast.LENGTH_SHORT).show();

    }
}

and activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}" >

    <fragment
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.MapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.simon.learning.googlemaptesting"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="21" />

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" />
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />

        <activity
            android:name=".MainActivity"
            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>

</manifest>

so please tell me how to do this??? Thanks in advance

Solution

You can calculate the distance in two locations on OnLocationChangedListener() with the function -

Location locationA = new Location("point A");     
locationA.setLatitude(latA); 
locationA.setLongitude(lngA);
Location locationB = new Location("point B");
locationB.setLatitude(latB); 
LocationB.setLongitude(lngB);
distance = locationA.distanceTo(locationB) ;

Answered By - Sumit T