如何在android中的expandableListView中更改按下的groupitem的颜色

Question

我在android中创建了一个非常简单的expandableList，现在我想点击该列表的groupitems时应该更改它的颜色，我尝试了下面的代码，但是没有用。请建议我该怎么做。 。 的 main.java     package com.example.expandablelistdemo;

import java.util.ArrayList;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.TextView;

public class MainActivity extends Activity {
ExpandableListView el;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    el=(ExpandableListView)findViewById(R.id.expandableListView1);
    Child c;

    Group group;
    String[] grup={"fruit","vehicle","cedans","animals"};
    ArrayList<Group> groups=new ArrayList<Group>();
    ArrayList<Child> childrens=new ArrayList<Child>();



    String[] fruit={"Apple","banana","Cherry","Orange"};
    String[] vehicle={"cycle","scooter","chopper","truck"};
    String[] cedans={"Bmw","jaguar","masserratti","Buggati","Karma"};
    String[] planes={"AirBus","Mig42","jet"};

    for(String str:grup){
        if(str.equalsIgnoreCase("fruit")){
            childrens =new ArrayList<Child>();
            for(String cname:fruit){
                Child child =new Child(cname, cname);
                childrens.add(child);

            }
        }
        else if(str.equalsIgnoreCase("vehicle")){
            childrens =new ArrayList<Child>();
            for(String cname:vehicle){
                Child child =new Child(cname, cname);
                childrens.add(child);
            }
        }
else if(str.equalsIgnoreCase("cedans")){
    childrens =new ArrayList<Child>();
    for(String cname:cedans){
        Child child =new Child(cname, cname);
        childrens.add(child);
    }
}
else if(str.equalsIgnoreCase("planes")){
    childrens =new ArrayList<Child>();
    for(String cname:planes){
        Child child =new Child(cname, cname);
        childrens.add(child);
    }
}  group = new Group(str, str, childrens);
groups.add(group);
    }


    ExpandableListAdapter ela =new ExpandableListAdapter(getApplicationContext(), groups);
    el.setAdapter(ela);

    el.setOnChildClickListener(new OnChildClickListener() {

        @Override
        public boolean onChildClick(ExpandableListView parent, View v,
                int groupPosition, int childPosition, long id) {

            ((TextView)v).setTextColor(Color.RED);
            return false;
        }
    });
    }



}