Using Google Maps with Sliding menu

Question

I'm using google maps with navigation drawer. Everything works fine on first load but when i switch the item, the application crashes. don't know why...Here is my log cat.

    02-22 15:00:19.847: E/AndroidRuntime(30597): FATAL EXCEPTION: main
02-22 15:00:19.847: E/AndroidRuntime(30597): java.lang.NullPointerException
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:651)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.os.Handler.handleCallback(Handler.java:725)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.os.Handler.dispatchMessage(Handler.java:92)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.os.Looper.loop(Looper.java:153)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at android.app.ActivityThread.main(ActivityThread.java:5299)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at java.lang.reflect.Method.invokeNative(Native Method)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at java.lang.reflect.Method.invoke(Method.java:511)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
02-22 15:00:19.847: E/AndroidRuntime(30597):    at dalvik.system.NativeStart.main(Native Method)

MapFragment :

import org.json.JSONException;
import org.json.JSONObject;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.InflateException;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.gol.apps.pickmedriver.classes.HttpClassHandler;
import com.gol.apps.pickmedriver.classes.Session;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapFragment extends Fragment implements LocationListener {

    private GoogleMap googleMap;
    private Location location;
    private LocationManager locationManager;
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 5; // 5 meters
    private static final long MIN_TIME_BW_UPDATES = 2000 * 60 * 1; // 2 minute
    private double latitude;
    private double longitude;
    boolean isGPSEnabled = false;
    boolean isNetworkEnabled = false;
    private SharedPreferences sp;
    boolean canGetLocation = false;
    private View view;
    private LatLng center;
    private HttpClassHandler handler;
    private Session session;
    private JSONObject jObj;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        if (container == null) {
            return null;
        }
        if (view != null) {
            ViewGroup parent = (ViewGroup) view.getParent();
            if (parent != null)
                parent.removeView(view);
        }
        try {
            view = inflater
                    .inflate(R.layout.activity_mapview, container, false);
            setUpMapIfNeeded();
        } catch (InflateException e) {
            // Log.wtf("S*****", e.getMessage());
        }

        initialize(view);
        return view;
    }

    public void setUpMapIfNeeded() {

        if (googleMap == null) {
            googleMap = ((SupportMapFragment) getActivity()
                    .getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();
        }
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        Fragment fragment = (getFragmentManager().findFragmentById(R.id.map));
        FragmentTransaction ft = getActivity().getSupportFragmentManager().beginTransaction();
        ft.remove(fragment);
        ft.commit();
        fragment = null;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        isGPSAvailable();
        location = getLocation();

        // Creating a LatLng object for the current location
        center = new LatLng(location.getLatitude(), location.getLongitude());
        // Showing the current location in Google Map
        googleMap.moveCamera(CameraUpdateFactory.newLatLng(center));

        MarkerOptions mp = new MarkerOptions();

        mp.position(new LatLng(location.getLatitude(), location.getLongitude()));

        mp.title("my position");
        mp.icon(BitmapDescriptorFactory.fromResource(R.drawable.marker));
        googleMap.addMarker(mp);
        // Zoom in the Google Map
        googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));
        updateCurrentLocationInDatabase(location);
    }

    private void initialize(View view) {
        handler = new HttpClassHandler();
        session = new Session(getActivity());
    }

    public double getLatitude() {
        if (location != null) {
            latitude = location.getLatitude();
        }

        // return latitude
        return latitude;
    }

    public double getLongitude() {
        if (location != null) {
            longitude = location.getLongitude();
        }

        // return longitude
        return longitude;
    }

    public boolean canGetLocation() {
        return this.canGetLocation;
    }

    /** this criteria will settle for less accuracy, high power, and cost */
    public static Criteria createCoarseCriteria() {

        Criteria c = new Criteria();
        c.setAccuracy(Criteria.ACCURACY_COARSE);
        c.setAltitudeRequired(false);
        c.setBearingRequired(false);
        c.setSpeedRequired(false);
        c.setCostAllowed(true);
        c.setPowerRequirement(Criteria.POWER_HIGH);
        return c;

    }

    /** this criteria needs high accuracy, high power, and cost */
    public static Criteria createFineCriteria() {

        Criteria c = new Criteria();
        c.setAccuracy(Criteria.ACCURACY_FINE);
        c.setAltitudeRequired(false);
        c.setBearingRequired(false);
        c.setSpeedRequired(false);
        c.setCostAllowed(true);
        c.setPowerRequirement(Criteria.POWER_HIGH);
        return c;

    }

    public Location getLocation() {
        try {

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

            isGPSEnabled = locationManager
                    .isProviderEnabled(LocationManager.GPS_PROVIDER);
            isNetworkEnabled = locationManager
                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            if (!isGPSEnabled && !isNetworkEnabled) {
                Toast.makeText(getActivity(), "No Provider is enabled",
                        Toast.LENGTH_LONG).show();
            } else {
                this.canGetLocation = true;

                if (isNetworkEnabled) {
                    LocationProvider high = locationManager
                            .getProvider(locationManager.getBestProvider(
                                    createFineCriteria(), isNetworkEnabled));
                    locationManager.requestLocationUpdates(high.getName(),
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.e("Network", "Network");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }

                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) {
                    if (location == null) {
                        LocationProvider high = locationManager
                                .getProvider(locationManager.getBestProvider(
                                        createFineCriteria(), isGPSEnabled));
                        locationManager.requestLocationUpdates(high.getName(),
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                        Log.d("GPS Enabled", "GPS Enabled");
                        if (locationManager != null) {
                            location = locationManager
                                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }

            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return location;
    }

    public void isGPSAvailable() {
        LocationManager manager = (LocationManager) getActivity()
                .getSystemService(Context.LOCATION_SERVICE);
        boolean statusOfGPS = manager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);
        if (!statusOfGPS) {
            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
                    getActivity());

            alertDialogBuilder.setTitle("No GPS");

            alertDialogBuilder
                    .setMessage(
                            "Your GPS does not seem to be active.Please check your Settings.")
                    .setIcon(R.drawable.bullet_error)
                    .setCancelable(false)
                    .setPositiveButton("Settings",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    startActivity(new Intent(
                                            android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
                                }
                            })
                    .setNegativeButton("ok",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    dialog.cancel();
                                }
                            });

            // create alert dialog
            AlertDialog alertDialog = alertDialogBuilder.create();

            // show it
            alertDialog.show();
        }
    }

    @Override
    public void onLocationChanged(Location arg0) {

        googleMap.clear();
        // Getting latitude of the current location
        latitude = location.getLatitude();

        // Getting longitude of the current location
        longitude = location.getLongitude();

        // Creating a LatLng object for the current location
        center = new LatLng(latitude, longitude);

        // Showing the current location in Google Map
        googleMap.moveCamera(CameraUpdateFactory.newLatLng(center));

        MarkerOptions mp = new MarkerOptions();

        mp.position(new LatLng(location.getLatitude(), location.getLongitude()));

        mp.title("my position");

        googleMap.addMarker(mp);
        // Zoom in the Google Map
        googleMap.animateCamera(CameraUpdateFactory.zoomTo(16));
        updateCurrentLocationInDatabase(location);

    }

    // Updating current location in the database
    public void updateCurrentLocationInDatabase(Location loc) {
        if (location != null) {
            jObj = handler.insertLocation(Double.toString(loc.getLatitude()),
                    Double.toString(loc.getLongitude()), session.getUserId());

            try {
                String msg = jObj.getString("success").toString();
                if (msg.equals("1")) {
                    // Toast.makeText(getActivity(),
                    // jObj.getString("msg").toString(),
                    // Toast.LENGTH_LONG).show();
                } else if (msg.equals("0")) {
                    Toast.makeText(getActivity(), jObj.getString("msg"),
                            Toast.LENGTH_LONG).show();
                }
            } catch (JSONException e) {

                e.printStackTrace();
            }
        }

    }

    @Override
    public void onProviderDisabled(String arg0) {
        Toast.makeText(getActivity(), "Providers Disabled!", Toast.LENGTH_LONG)
                .show();

    }

    @Override
    public void onProviderEnabled(String arg0) {
        Toast.makeText(getActivity(), "Providers Enabled!", Toast.LENGTH_LONG)
                .show();

    }

    @Override
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
        // TODO Auto-generated method stub

    }

}

NavigationDrawer:

import java.util.ArrayList;

import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.res.Configuration;
import android.content.res.TypedArray;
import android.os.Build;
import android.os.Bundle;
import android.os.StrictMode;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.text.SpannableString;
import android.text.util.Linkify;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;

import com.actionbarsherlock.app.SherlockFragmentActivity;
import com.actionbarsherlock.view.Menu;
import com.actionbarsherlock.view.MenuInflater;
import com.gol.apps.pickmedriver.adapters.NavDrawerListAdapter;
import com.gol.apps.pickmedriver.classes.NavDrawerItem;
import com.gol.apps.pickmedriver.classes.Session;

public class NavigationDrawerActivity extends SherlockFragmentActivity {

    private DrawerLayout mDrawerLayout;
    private ActionBarDrawerToggle mDrawerToggle;
    private ListView mDrawerList;

    // slide menu items
    private String[] navMenuTitles;
    private TypedArray navMenuIcons;

    private ArrayList<NavDrawerItem> navDrawerItems;
    private NavDrawerListAdapter adapter;
    private Fragment content;
    private Session session;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_navigation_drawer);
        strickMode();
        initialize();
        clicklistners();
        if (savedInstanceState == null) {
            selectItem(0);
        }
    }

    @SuppressLint("NewApi")
    private void initialize() {
        session = new Session(NavigationDrawerActivity.this);
        navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);

        // nav drawer icons from resources
        navMenuIcons = getResources()
                .obtainTypedArray(R.array.nav_drawer_icons);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.drawer_list);
        View headerView = ((LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE))
                .inflate(R.layout.nav_drawer_list_header, null, false);
        mDrawerList.addHeaderView(headerView);
        navDrawerItems = new ArrayList<NavDrawerItem>();
        navDrawerItems = new ArrayList<NavDrawerItem>();

        navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons
                .getResourceId(0, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons
                .getResourceId(1, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons
                .getResourceId(2, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons
                .getResourceId(3, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons
                .getResourceId(4, -1)));

        // Recycle the typed array
        navMenuIcons.recycle();
        adapter = new NavDrawerListAdapter(getApplicationContext(),
                navDrawerItems);
        mDrawerList.setAdapter(adapter);
        mDrawerLayout.setDrawerListener(mDrawerToggle);
        mDrawerList.setItemChecked(0, true);
        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                R.drawable.navigation_drawer, R.string.app_name,
                R.string.app_name) {

            /** Called when a drawer has settled in a completely closed state. */
            @SuppressLint("NewApi")
            public void onDrawerClosed(View view) {
                super.onDrawerClosed(view);
            }

            /** Called when a drawer has settled in a completely open state. */
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        mDrawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggls
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    private void clicklistners() {
        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);

    }

    private class DrawerItemClickListener implements
            ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            selectItem(position);
        }
    }

    private void selectItem(int position) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        switch (position) {
        case 0:
            content = new TabsMainActivity();
            ft.replace(R.id.content_frame, content).commit();
            break;
        case 1:
            content = new BookingTabsActivity();
            ft.replace(R.id.content_frame, content).commit();
            break;
        case 2:
            content = new MapFragment();
            ft.replace(R.id.content_frame, content).commit();
            break;
        case 3:
            content = new UserLocationHistoryActivity();
            ft.replace(R.id.content_frame, content).commit();
            break;
        case 4:
            content = new MapFragment();
            ft.replace(R.id.content_frame, content).commit();
            break;
        case 5:
            shareIt();
            break;
        }
        mDrawerList.setItemChecked(position, true);
        mDrawerList.setSelection(position);
        mDrawerLayout.closeDrawer(mDrawerList);

    }

    public void onDestroy() {
        super.onDestroy();
        Log.d("DEBUG", "In Method: onDestroy()");
    }

    @Override
    public void onResume() {
        super.onResume();
    }

    private void shareIt() {
        Intent sharingIntent = new Intent(android.content.Intent.ACTION_SEND);
        sharingIntent.setType("text/plain");
        String shareBody = "Hey! I start using PickMeDriver";
        sharingIntent.putExtra(android.content.Intent.EXTRA_SUBJECT,
                "PickMeDriver");
        sharingIntent.putExtra(android.content.Intent.EXTRA_TEXT, shareBody);
        startActivity(Intent.createChooser(sharingIntent, "Share PickMeDriver"));

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getSupportMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true;
    }

    public boolean onOptionsItemSelected(
            com.actionbarsherlock.view.MenuItem item) {

        if (item.getItemId() == android.R.id.home) {

            if (mDrawerLayout.isDrawerOpen(mDrawerList)) {
                mDrawerLayout.closeDrawer(mDrawerList);
            } else {
                mDrawerLayout.openDrawer(mDrawerList);
            }
        }
        switch (item.getItemId()) {
        case R.id.about:
            final SpannableString s = new SpannableString(
                    NavigationDrawerActivity.this
                            .getText(R.string.dialogue_message));
            Linkify.addLinks(s, Linkify.WEB_URLS);
            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
                    NavigationDrawerActivity.this);
            alertDialogBuilder.setTitle("About");
            alertDialogBuilder
                    .setMessage(s)
                    .setCancelable(false)
                    .setNegativeButton("Ok",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    dialog.cancel();
                                }
                            });
            // create alert dialog
            AlertDialog alertDialog = alertDialogBuilder.create();
            // show it
            alertDialog.show();
            return true;
        case R.id.sign_out:
            session.distroySession();
            Intent i = new Intent(NavigationDrawerActivity.this,
                    MainActivity.class);
            startActivity(i);
            finish();
            return true;

        case android.R.id.home:
            if (mDrawerLayout.isDrawerOpen(mDrawerList))
                mDrawerLayout.closeDrawer(mDrawerList);
            else {
                mDrawerLayout.openDrawer(mDrawerList);
                mDrawerLayout.openDrawer(Gravity.LEFT);
            }
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }

    }

    @TargetApi(Build.VERSION_CODES.GINGERBREAD)
    @SuppressLint("NewApi")
    private void strickMode() {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
                .permitAll().build();
        StrictMode.setThreadPolicy(policy);
    }
}