Shared Preference does not remember value of checkbox

I have written code that displays list of installed apps along with checkbox. I have used sharedpreference to save value of checkboxes. However, it doesnt remember value and value resets every time I close the app.The code is posted below. What am I doing wrong? Thanks in advance!!

MainActivity.java

public class MainActivity extends ListActivity {
    private PackageManager packageManager = null;
    private List<ApplicationInfo> applist = null;
    private ApplicationAdapter listadapter = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        packageManager = getPackageManager();

        new LoadApplications().execute();
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);

        ApplicationInfo app = applist.get(position);
        try {
            Intent intent = packageManager
                    .getLaunchIntentForPackage(app.packageName);

            if (null != intent) {
                startActivity(intent);
            }
        } catch (ActivityNotFoundException e) {
            Toast.makeText(MainActivity.this, e.getMessage(),
                    Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            Toast.makeText(MainActivity.this, e.getMessage(),
                    Toast.LENGTH_LONG).show();
        }
    }

    private List<ApplicationInfo> checkForLaunchIntent(List<ApplicationInfo> list) {
        ArrayList<ApplicationInfo> applist = new ArrayList<ApplicationInfo>();
        for (ApplicationInfo info : list) {
            try {
                if (null != packageManager.getLaunchIntentForPackage(info.packageName)) {
                    applist.add(info);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        return applist;
    }

    private class LoadApplications extends AsyncTask<Void, Void, Void> {
        private ProgressDialog progress = null;

        @Override
        protected Void doInBackground(Void... params) {
            applist = checkForLaunchIntent(packageManager.getInstalledApplications(PackageManager.GET_META_DATA));
            listadapter = new ApplicationAdapter(MainActivity.this,
                    R.layout.row, applist);

            return null;
        }

        @Override
        protected void onCancelled() {
            super.onCancelled();
        }

        @Override
        protected void onPostExecute(Void result) {
            setListAdapter(listadapter);
            progress.dismiss();
            super.onPostExecute(result);
        }

        @Override
        protected void onPreExecute() {
            progress = ProgressDialog.show(MainActivity.this, null,
                    "Loading application info...");
            super.onPreExecute();
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);
        }
    }
}

ApplicationAdapter.java

import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.TextView;

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

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
    private List<ApplicationInfo> appsList = null;
    private Context context;
    private PackageManager packageManager;
    private SharedPreferences prefs;
    public ApplicationAdapter(Context context, int textViewResourceId,
                              List<ApplicationInfo> appsList) {
        super(context, textViewResourceId, appsList);
        this.context = context;
        this.appsList = appsList;
        packageManager = context.getPackageManager();
        prefs = context.getSharedPreferences("checkboxstate",Context.MODE_PRIVATE);
    }



    @Override
    public int getCount() {
        return ((null != appsList) ? appsList.size() : 0);
    }

    @Override
    public ApplicationInfo getItem(int position) {
        return ((null != appsList) ? appsList.get(position) : null);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (null == view) {
            LayoutInflater layoutInflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = layoutInflater.inflate(R.layout.row, null);
        }

        ApplicationInfo data = appsList.get(position);
        if (null != data) {
            TextView appName = (TextView) view.findViewById(R.id.app_name);
            TextView packageName = (TextView) view.findViewById(R.id.app_package);
            ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

            CheckBox checkBox = (CheckBox) view.findViewById(R.id.cb_app);
            checkBox.setTag(String.valueOf(appName)); // set the tag so we can identify the correct row in the listener
            checkBox.setChecked(prefs.getBoolean(checkBox.getTag().toString(), false)); // set the status as we stored it

            checkBox.setOnClickListener(onclicklistener);
            appName.setText(data.loadLabel(packageManager));
            packageName.setText(data.packageName);
            iconview.setImageDrawable(data.loadIcon(packageManager));
        }
        return view;
}

    CheckBox.OnClickListener onclicklistener = new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            prefs.edit().putBoolean(v.getTag().toString(),((CheckBox)v).isChecked()).apply();

        }
    };
}

activity_main.xml

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

    </ListView>

</LinearLayout>

row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://ift.tt/nIICcg"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <ImageView
        android:id="@+id/app_icon"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:scaleType="centerCrop"
        android:padding="3dp"
        android:src="@drawable/download" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:orientation="vertical"
        android:paddingLeft="5dp" >

        <TextView
            android:id="@+id/app_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center_vertical"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/app_package"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center_vertical" />
    </LinearLayout>


    <CheckBox
        android:id="@+id/cb_app"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>