how to set checked the checkbox when click on the list item?

sorry for my bad english I'm working on an app that display a list of installed apps. I added checkbox to each item of this list for select apps the problem is when i set one of the checkbox state to checked and scroll down, i see some other the checkboxes state has been changed to check how can i solve this problem?? this is my codes

the AllAppsActivity.java codes:

import java.util.ArrayList;
import java.util.List;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import android.widget.ListView;


public class AllAppsActivity extends ListActivity {

private PackageManager packageManager = null;
private List<ApplicationInfo> applist = null;
private ApplicationAdapter listadaptor = 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);

    if (v != null) {
        CheckBox checkBox = (CheckBox) v.findViewById(R.id.checkBox);
        checkBox.setChecked(!checkBox.isChecked());
    }



}

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));
        listadaptor = new ApplicationAdapter(AllAppsActivity.this,
                R.layout.snippet_list_row, applist);

        return null;
    }

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

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

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

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

the ApplicationAdapter.java codes:

import java.util.List;
import android.content.Context;
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.ImageView;
import android.widget.TextView;

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
private List<ApplicationInfo> appsList = null;
private Context context;
private PackageManager packageManager;

public ApplicationAdapter(Context context, int textViewResourceId,
        List<ApplicationInfo> appsList) {
    super(context, textViewResourceId, appsList);
    this.context = context;
    this.appsList = appsList;
    packageManager = context.getPackageManager();
}

@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.snippet_list_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_paackage);
        ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

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

activity_main.xml file:

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

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

and snippet_list_row.xml codes:

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

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

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    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_paackage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical" />
</LinearLayout>

<CheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/checkBox"
    android:focusable="false" />

please help me to solve this problem