Creating Location Client in Android API 19 - location-client

Question

I have been making an application that saves user location in a string,
First of all I need to Define Location Services Callbacks,
for Connecting the Location Client, I need to create a Location Client in OnCreate() method of my Application,
so I have used the below code as my Main.java File:
As you see, the Location Client function mLocationClient.connect(); is called in OnStart() method of the activity,
and that makes the application to Force Stop.
package ir.superus8r.location3;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesClient;
import com.google.android.gms.location.LocationClient;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.test.suitebuilder.TestSuiteBuilder.FailedToCreateTests;
import android.content.IntentSender;
import android.location.Location;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import android.os.Build;
public class MainActivity extends FragmentActivity implements
GooglePlayServicesClient.ConnectionCallbacks,
GooglePlayServicesClient.OnConnectionFailedListener {
private static final int CONNECTION_FAILURE_RESOLUTION_REQUEST = 0;
LocationClient mLocationClient;
TextView tv01 = (TextView) findViewById(R.id.tvwtf);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
mLocationClient = new LocationClient(this, this, this);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
#Override
public void onConnectionFailed(ConnectionResult connectionResult) {
// TODO Auto-generated method stub
if(connectionResult.hasResolution()){
try{
//activity that tries to resolve the error
connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
} catch (IntentSender.SendIntentException e){
//error log
e.printStackTrace();
}
} else {
tv01.setText("Unknown Error!");
}
}
#Override
public void onConnected(Bundle dataBundle) {
// TODO Auto-generated method stub
// displaying the connection status
Toast.makeText(this, "Connected", Toast.LENGTH_SHORT).show();
}
#Override
public void onDisconnected() {
// TODO Auto-generated method stub
// Display the connection status
Toast.makeText(this, "Disconnected. Please re-connect.",
Toast.LENGTH_SHORT).show();
}
#Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
mLocationClient.connect();
}
}
Here's the LogCat output:
07-03 07:13:15.557: D/AndroidRuntime(28102): Shutting down VM
07-03 07:13:15.557: W/dalvikvm(28102): threadid=1: thread exiting with uncaught exception (group=0x41b978b0)
07-03 07:13:15.567: E/AndroidRuntime(28102): FATAL EXCEPTION: main
07-03 07:13:15.567: E/AndroidRuntime(28102): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{ir.superus8r.location3/ir.superus8r.location3.MainActivity}: java.lang.NullPointerException
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2192)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2316)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.ActivityThread.access$600(ActivityThread.java:150)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1298)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.os.Handler.dispatchMessage(Handler.java:99)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.os.Looper.loop(Looper.java:213)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.ActivityThread.main(ActivityThread.java:5225)
07-03 07:13:15.567: E/AndroidRuntime(28102): at java.lang.reflect.Method.invokeNative(Native Method)
07-03 07:13:15.567: E/AndroidRuntime(28102): at java.lang.reflect.Method.invoke(Method.java:525)
07-03 07:13:15.567: E/AndroidRuntime(28102): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-03 07:13:15.567: E/AndroidRuntime(28102): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
07-03 07:13:15.567: E/AndroidRuntime(28102): at dalvik.system.NativeStart.main(Native Method)
07-03 07:13:15.567: E/AndroidRuntime(28102): Caused by: java.lang.NullPointerException
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.Activity.findViewById(Activity.java:1853)
07-03 07:13:15.567: E/AndroidRuntime(28102): at ir.superus8r.location3.MainActivity.<init>(MainActivity.java:29)
07-03 07:13:15.567: E/AndroidRuntime(28102): at java.lang.Class.newInstanceImpl(Native Method)
07-03 07:13:15.567: E/AndroidRuntime(28102): at java.lang.Class.newInstance(Class.java:1130)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
07-03 07:13:15.567: E/AndroidRuntime(28102): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2183)
07-03 07:13:15.567: E/AndroidRuntime(28102): ... 11 more
Any helps will be appreciated,
Thanks in advance.

Answer 1

You can use the condition while creating locationClient object.
onStart(){
if(mLocationClient==null){
mLocationClient = new LocationClient(this, this, this);
}
mLocationClient.connect();
}
Else if onStart is not compulsary call mLocationClient.connect() in onCreate() itself;