I want to get instance of action bar but getting the value null and because of that my whole program is not running.
My code where I have included this method is:
When my code jumps to line where action bar is needed it gives me null pointer exception
HomeTab.java:
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
public class HomeTab extends Activity implements OnItemClickListener{
    MyCustomAdapter myCustomAdapter;
    Context context=HomeTab.this;
    //ImageView menuimage;
    String optionName[]=new String[] {"Alerts","Events","Newsletters","News","Parent Info","Logins","Parent Teacher Interviews","Flexi School LunchOrder","Contact US","Kool Content"};
    //int image[]=new int[] {R.drawable.alert_small_icon,R.drawable.events,R.drawable.newsletter,R.drawable.newsletter,R.drawable.arrow_24,R.drawable.arrow_24,R.drawable.arrow_24,R.drawable.arrow_24,R.drawable.arrow_24,R.drawable.arrow_24};
    int imageArrow[]=new int[]{R.drawable.right_arrow};
    ArrayList<ListModel> mylist=new ArrayList<ListModel>();
    // test for sliding drawer
    /*
    String[] menu;
    DrawerLayout dLayout;
    ListView dList;
    ArrayAdapter<String> adapter;*/
    /*
     * code from leftslide
     * 
     */
    private DrawerLayout mDrawerLayout;
    public ListView DrawerList;
    private ActionBarDrawerToggle mDrawerToggle;
 // nav drawer title
    private CharSequence mDrawerTitle;
    // used to store app title
    private CharSequence mTitle;
    // slide menu items
    private String[] navMenuTitles;
    private TypedArray navMenuIcons;
    private ArrayList<NavDrawerItem> navDrawerItems;
    private NavDrawerListAdapter adapter;
    LayoutInflater inflater=null;
    // code upto left slide
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.list_view_layout);
        //menuimage=(ImageView)findViewById(R.id.menuimage);
        //new code below
        /*menuimage=(ImageView)findViewById(R.id.menuimage);
        adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,menu);
        menu = new String[]{"Home","Android","Windows","Linux","Raspberry Pi","WordPress","Videos","Contact Us"};
        dLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        dList = (ListView) findViewById(R.id.left_drawer);*/
        //new above
        ListView listview=(ListView)findViewById(R.id.listView1);
        getDatainList();
        listview.setAdapter(new MyCustomAdapter(context, mylist));
        listview.setBackgroundColor(Color.WHITE);
        listview.setOnItemClickListener(this);
        inflater=(LayoutInflater)HomeTab.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View vi=inflater.inflate(com.example.testlist.R.layout.sliding_activity_main, null);
        mTitle = mDrawerTitle = getTitle();
        // load slide menu items
        navMenuTitles = getResources().getStringArray(com.example.testlist.R.array.nav_drawer_items);
         //nav drawer icons from resources
        navMenuIcons = getResources()
                .obtainTypedArray(com.example.testlist.R.array.nav_drawer_icons);
        mDrawerLayout = (DrawerLayout) vi.findViewById(R.id.drawer_layout);
        DrawerList = (ListView) vi.findViewById(R.id.left_draw);
        DrawerList.setOnItemClickListener(new OnItemClickListener() 
        {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
//               displayView(position);
                Toast.makeText(getApplicationContext(), "hi", 300).show();
            }
        }); 
        navDrawerItems = new ArrayList<com.ctpl.skoolbag.leftslide.NavDrawerItem>();
        // adding nav drawer items to array
        // Home
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[0],navMenuIcons.getResourceId(0, -1)));
        // Find People
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[1],navMenuIcons.getResourceId(1, -1)));
        // Photos
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[2],navMenuIcons.getResourceId(2, -1)));
        // Communities, Will add a counter here
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[3],navMenuIcons.getResourceId(3, -1)));
        // Pages
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[4],navMenuIcons.getResourceId(4, -1)));
        // What's hot, We  will add a counter here
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[5],navMenuIcons.getResourceId(5, -1)));
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[6],navMenuIcons.getResourceId(6, -1)));
        navDrawerItems.add(new com.ctpl.skoolbag.leftslide.NavDrawerItem(navMenuTitles[7],navMenuIcons.getResourceId(7, -1)));
        // Recycle the typed array
        navMenuIcons.recycle();
        // setting the nav drawer list adapter
        adapter = new com.ctpl.skoolbag.leftslide.NavDrawerListAdapter(getApplicationContext(),
                navDrawerItems);
        DrawerList.setAdapter(adapter);
        // enabling action bar app icon and behaving it as toggle button
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);
        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                R.drawable.cat, //nav menu toggle icon
                R.string.app_name, // nav drawer open - description for accessibility
                R.string.app_name // nav drawer close - description for accessibility
        ){
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                // calling onPrepareOptionsMenu() to show action bar icons
                invalidateOptionsMenu();
            }
            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mDrawerTitle);
                // calling onPrepareOptionsMenu() to hide action bar icons
                invalidateOptionsMenu();
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);
        if (savedInstanceState == null) {
            // on first time display view for first nav item
            displayView(0);
        }
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.left_slide, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // toggle nav drawer on selecting action bar app icon/title
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        // Handle action bar actions click
        switch (item.getItemId()) {
        case R.id.action_settings:
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }
    /***
     * Called when invalidateOptionsMenu() is triggered
     */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // if nav drawer is opened, hide the action items
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(DrawerList);
        menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
        return super.onPrepareOptionsMenu(menu);
    }
    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        getActionBar().setTitle(mTitle);
    }
    /**
     * When using the ActionBarDrawerToggle, you must call it during
     * onPostCreate() and onConfigurationChanged()...
     */
    @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 getDatainList() 
    {
        for(int i=0;i<10;i++)
        {
            ListModel li=new ListModel();
            li.setOptionName(optionName[i]);
        //  li.setImage(image[i]);
            li.setImageArrow(R.drawable.arrow);
            mylist.add(li);
        }
    }
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) 
    {
        switch (position) {
        case 0:
            Intent call_AlertWebService=new Intent(getApplicationContext(),AlertActivityFromService.class);
            startActivity(call_AlertWebService);
            break;
        case 1:
            Intent i=new Intent(getApplicationContext(),EventsFromWebService.class);
            startActivity(i);
            break;
        case 2:
            Intent in=new Intent(getApplicationContext(),NewslettersActivityFromService.class);
            startActivity(in);
            break;
        case 3:
            Intent inn=new Intent(getApplicationContext(),NewsFromService.class);
            startActivity(inn);
            break;
        default:
            break;
        }
    }
/**
* Diplaying fragment view for selected nav drawer list item
* */
private void displayView(int position) {
// update the main content by replacing fragments
android.app.Fragment fragment = null;
switch (position) {
case 0:
    fragment = new HomeFragment();
    break;
/*case 1:
    fragment = new FindPeopleFragment();
    break;
case 2:
    fragment = new PhotosFragment();
    break;
case 3:
    fragment = new CommunityFragment();
    break;
case 4:
    fragment = new PagesFragment();
    break;
case 5:
    fragment = new WhatsHotFragment();
    break;
*/
default:
    break;
}
if (fragment != null) {
    android.app.FragmentManager fragmentManager = getFragmentManager();
    fragmentManager.beginTransaction()
            .replace(com.example.testlist.R.id.content_frame, fragment).commit();
    // update selected item and title, then close the drawer
    DrawerList.setItemChecked(position, true);
    DrawerList.setSelection(position);
    setTitle(navMenuTitles[position]);
    mDrawerLayout.closeDrawer(DrawerList);
} else {
    // error in creating fragment
    Log.e("MainActivity", "Error in creating fragment");
}
}
}
 
    