Cannot get it work with the fragments.

[vakasgnabi]

package com.peekatuts.inductin;

import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.google.gson.Gson;
import com.kosalgeek.genasync12.AsyncResponse;
import com.kosalgeek.genasync12.PostResponseAsyncTask;

import java.util.ArrayList;
import java.util.List;

public class Courses_ListView extends Fragment implements AsyncResponse {
//final String LOG="Courses_ListView";

final String LOG="Courses_ListView";
public ListView mListView;
List<String> items = new ArrayList<String>();
public String str = "";
DatabaseManagement dm=new DatabaseManagement(getContext());

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
    View v=inflater.inflate(R.layout.fragment_courses_list_view,container,false);

    return v;

}



@Override
public void onStart() {
    super.onStart();
    initControls();
}

public void initControls(){
    mListView = (ListView) getView().findViewById(R.id.courseList);
    PostResponseAsyncTask taskRead = new PostResponseAsyncTask(getContext(),this);
    taskRead.execute("http://www.inductin.com/webservices/course_categories.php?request=ios");
    populateListView();
}



@Override
public void processFinish(String s) {
    Gson g=new Gson();

    Courses c=g.fromJson(s,Courses.class);
    Datum d=g.fromJson(s,Datum.class);
    int count=c.getData().toArray().length;
    // Toast.makeText(Courses_ListView.this, ""+count, Toast.LENGTH_SHORT).show();

    Cursor res=dm.getAllData(dm,"SELECT * FROM course_categories");

    int getCount=res.getCount();

    if(getCount==0) {
        for (int i = 0; i <= count; i++) {
            boolean insert = dm.onInsert(dm, c.getData().get(i).getCategoryId(), c.getData().get(i).getCategoryName());
            if (insert == true) {
                Log.i("Database front end:", "Data has been inserted successfully");
            } else {
                Log.i("Database front end:", "Insert issue");
            }
        }
    }
    else if(count!=getCount){
        dm.deleteAllData(dm,"course_categories");
        for (int i = 0; i <= count; i++) {
            boolean insert = dm.onInsert(dm, c.getData().get(i).getCategoryId(), c.getData().get(i).getCategoryName());
            if (insert == true) {
                Log.i("Database front end:", "Data has been inserted successfully");
            } else {
                Log.i("Database front end:", "Insert issue");
            }
        }
    }

}



private void populateListView(){
    Cursor cursor=dm.getAllRows(dm,"SELECT category_name FROM course_categories");
    for( cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext() ) {
        items.add(cursor.getString(0));
    }




    ArrayAdapter<String> adapter= new ArrayAdapter<String>(getContext(), android.R.layout.simple_list_item_1,items);
    mListView.setAdapter(adapter);
    mListView.setOnItemClickListener(new AdapterView.OnItemClickListener(){
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long l){
            str= items.get(position);

                Toast.makeText(getContext(),"You clicked:"+items.get(position),Toast.LENGTH_SHORT).show();



        }
    });
}

}

The above is my code. if something is wrong with my code then let me know but everytime i start my application and click on the option of the navigation drawer. The application closes.