مشکل با لیست ویو باز شدنی

adapter

import java.util.HashMap;
import java.util.List;

import com.hetbo.riazi_hashtom.R;

import android.content.Context;
import android.graphics.Typeface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

public class ExpandableListAdapter extends BaseExpandableListAdapter {

 private Context _context;
 private List<String> _listDataHeader; // header titles
 // child data in format of header title, child title
 private HashMap<String, List<String>> _listDataChild;

 public ExpandableListAdapter(Context context, List<String> listDataHeader,
 HashMap<String, List<String>> listChildData) {
 this._context = context;
 this._listDataHeader = listDataHeader;
 this._listDataChild = listChildData;
 }

 @Override
 public Object getChild(int groupPosition, int childPosititon) {
 retu this._listDataChild.get(this._listDataHeader.get(groupPosition))
 .get(childPosititon);
 }

 @Override
 public long getChildId(int groupPosition, int childPosition) {
 retu childPosition;
 }

 @Override
 public View getChildView(int groupPosition, final int childPosition,
 boolean isLastChild, View convertView, ViewGroup parent) {

 final String childText = (String) getChild(groupPosition, childPosition);

 if (convertView == null) {
 LayoutInflater infalInflater = (LayoutInflater) this._context
 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 convertView = infalInflater.inflate(R.layout.list_item, null);
 }

 TextView txtListChild = (TextView) convertView
 .findViewById(R.id.lblListItem);

 txtListChild.setText(childText);
 retu convertView;
 }

 @Override
 public int getChildrenCount(int groupPosition) {
 retu this._listDataChild.get(this._listDataHeader.get(groupPosition))
 .size();
 }

 @Override
 public Object getGroup(int groupPosition) {
 retu this._listDataHeader.get(groupPosition);
 }

 @Override
 public int getGroupCount() {
 retu this._listDataHeader.size();
 }

 @Override
 public long getGroupId(int groupPosition) {
 retu groupPosition;
 }

 @Override
 public View getGroupView(int groupPosition, boolean isExpanded,
 View convertView, ViewGroup parent) {
 String headerTitle = (String) getGroup(groupPosition);
 if (convertView == null) {
 LayoutInflater infalInflater = (LayoutInflater) this._context
 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 convertView = infalInflater.inflate(R.layout.list_group, null);
 }

 TextView lblListHeader = (TextView) convertView
 .findViewById(R.id.lblListHeader);
 lblListHeader.setTypeface(null, Typeface.BOLD);
 lblListHeader.setText(headerTitle);

 retu convertView;
 }

 @Override
 public boolean hasStableIds() {
 retu false;
 }

 @Override
 public boolean isChildSelectable(int groupPosition, int childPosition) {
 retu true;
 }

}

main activity

    ExpandableListAdapter listAdapter;
    ExpandableListView expListView;
    List<String> listDataHeader;
    HashMap<String, List<String>> listDataChild;


     @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        expListView = (ExpandableListView) findViewById(R.id.lvExp);
        
        prepareListData();
 
        listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild);
 
        expListView.setAdapter(listAdapter);
    }
   
    private void prepareListData() {
        listDataHeader = new ArrayList<String>();
        listDataChild = new HashMap<String, List<String>>();
 
        listDataHeader.add("فصل اول");
        listDataHeader.add("فصل دوم");
        listDataHeader.add("فصل سوم");
 
        List<String> sea01 = new ArrayList<String>();
        sea01.add("بخش اول");
        sea01.add("بخش دوم");
        sea01.add("بخش سوم");
        sea01.add("بخش چهارم");
        
        List<String> sea02 = new ArrayList<String>();
        sea02.add("بخش اول");
        sea02.add("بخش دوم");
 
        List<String> sea03 = new ArrayList<String>();
        sea03.add("بخش اول");
        sea03.add("بخش دوم");
        sea03.add("بخش سوم");
        sea03.add("بخش چهارم");
        sea03.add("بخش پنجم");
 
        listDataChild.put(listDataHeader.get(0), sea01);
        listDataChild.put(listDataHeader.get(1), sea02);
        listDataChild.put(listDataHeader.get(2), sea03);
    
        expListView.setOnChildClickListener(new OnChildClickListener() {
 
 @Override
 public boolean onChildClick(ExpandableListView parent, View v, int groupPosition,
 int childPosition, long id) {
 retu false;
 }
 });
    
    }

---

list group.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="8dp"
    android:background="#0097A7">
 
 
    <TextView
        android:id="@+id/lblListHeader"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="?android:attr/expandableListPreferredItemPaddingLeft"
        android:textSize="17dp"
        android:textColor="#E1F5FE" />
 
</LinearLayout>

list item . xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    
     <TextView
        android:id="@+id/lblListItem"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="17dip"
        android:paddingTop="5dp"
        android:paddingBottom="5dp"
        android:paddingLeft="?android:attr/expandableListPreferredChildPaddingLeft" />

</LinearLayout>