CheckBoxes automatically unchecked when ExpandableListView is expanding

public class ApisimpleActivity extends ExpandableListActivity {

    ExpandableListAdapter mAdapter;
Button btn;
CheckBox chk1;
String l="";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Set up our adapter
        setContentView(R.layout.main);
        btn=(Button)findViewById(R.id.button);
        btn.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
            int i=getExpandableListView().getChildCount();  
            int k=0;
            //Toast.makeText(ApisimpleActivity.this, "hello"+i, Toast.LENGTH_LONG).show();

            Toast.makeText(ApisimpleActivity.this, k+"",Toast.LENGTH_LONG).show();
            }      });
        mAdapter = new MyExpandableListAdapter();
        setListAdapter(mAdapter);
        registerForContextMenu(getExpandableListView());
    }

    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
        menu.setHeaderTitle("Sample menu");
        menu.add(0, 0, 0, "Hello World");
    }

    @Override
    public boolean onContextItemSelected(MenuItem item) {
        ExpandableListContextMenuInfo info = (ExpandableListContextMenuInfo) item.getMenuInfo();

        String title = ((TextView) info.targetView).getText().toString();

        int type = ExpandableListView.getPackedPositionType(info.packedPosition);
        if (type == ExpandableListView.PACKED_POSITION_TYPE_CHILD) {
            int groupPos = ExpandableListView.getPackedPositionGroup(info.packedPosition); 
            int childPos = ExpandableListView.getPackedPositionChild(info.packedPosition); 
            Toast.makeText(this, title + ": Child " + childPos + " clicked in group " + groupPos,
                    Toast.LENGTH_SHORT).show();
            return true;
        } else if (type == ExpandableListView.PACKED_POSITION_TYPE_GROUP) {
            int groupPos = ExpandableListView.getPackedPositionGroup(info.packedPosition); 
            Toast.makeText(this, title + ": Group " + groupPos + " clicked", Toast.LENGTH_SHORT).show();
            return true;
        }

        return false;
    }

    /**
     * A simple adapter which maintains an ArrayList of photo resource Ids. 
     * Each photo is displayed as an image. This adapter supports clearing the
     * list of photos and adding a new photo.
     *
     */
    public class MyExpandableListAdapter extends BaseExpandableListAdapter {
        // Sample data set.  children[i] contains the children (String[]) for groups[i].
        private String[] groups = { "People Names", "Dog Names", "Cat Names", "Fish Names" };
        private String[][] children = {
                { "Arnold", "Barry", "Chuck", "David" },
                { "Ace", "Bandit", "Cha-Cha", "Deuce" },
                { "Fluffy", "Snuggles" },
                { "Goldy", "Bubbles" }
        };
        View v;


        public Object getChild(int groupPosition, int childPosition) {
            return children[groupPosition][childPosition];
        }

        public long getChildId(int groupPosition, int childPosition) {
            return childPosition;
        }

        public int getChildrenCount(int groupPosition) {
            return children[groupPosition].length;
        }

        public TextView getGenericView() {
            // Layout parameters for the ExpandableListView
            AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
                    ViewGroup.LayoutParams.FILL_PARENT, 64);

            TextView textView = new TextView(ApisimpleActivity.this);
            textView.setLayoutParams(lp);
            // Center the text vertically
            textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
            // Set the text starting position
            textView.setPadding(36, 0, 0, 0);
            return textView;
        }

        public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
                View convertView, ViewGroup parent) {
            TextView textView = getGenericView();
            textView.setText(getChild(groupPosition, childPosition).toString());
            return textView;
        }

        public Object getGroup(int groupPosition) {
      开发者_开发问答      return groups[groupPosition];
        }

        public int getGroupCount() {
            return groups.length;
        }

        public long getGroupId(int groupPosition) {
            return groupPosition;
        }

        public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
                ViewGroup parent) {
            v = null;
            v=convertView;
            if(v==null)
             {LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
             v = vi.inflate(R.layout.group, null);
        /*   chk1 =(CheckBox)((View)v).findViewById(R.id.chk);
             chk1.setOnCheckedChangeListener(new OnCheckedChangeListener()
             {

                @Override
                public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
                    TextView txt = null;
                    if(arg0.isChecked()==true)
                    {
                        txt=(TextView) v.findViewById(R.id.txt);
                    l+=txt.getText().toString();
                    Toast.makeText(ApisimpleActivity.this,l, Toast.LENGTH_LONG).show();
                    }

                }

             });*/
             }
        return v;}

        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }

        public boolean hasStableIds() {
            return true;
        }

    }
}

hi this is my code its working fine showing me all children but the problem is in groupview there is a checkbox when i click on any check box and then expand it.it become unchecked any one can tell me the reason why it is unchecked on expanding the list and how to fix this problem. please help in solving this problem.

It may help you. take checkbox static and if you use multiple check box then use stringbuilder for store checked value.