Android BaseAdapter应用实例

/*** 生成联系人Items，即Items中包含如下控件**/public final class ViewHolder{  public ImageView callImg;//打电话的图标  public ImageView headImg;//头像  public TextView peopleName;//联系人名  public TextView peopleNumber;//联系人号码}public class MyAdapter extends BaseAdapter { private LayoutInflater mInflater; public MyAdapter(Context context) {  this.mInflater = LayoutInflater.from(context); } public int getCount() {   return listPeople.size(); } public Object getItem(int arg0) {   return listPeople.get(arg0); } public long getItemId(int arg0) {  return arg0;//当初在看别人例子时，此处返回NUll，加载都没问题，但在ListView中的OnItemsClick事件中就报错了。 } public View getView(final int position, View convertView,  ViewGroup parent) {  ViewHolder holder = null;  if (convertView == null) {  holder = new ViewHolder();  convertView = mInflater.inflate(R.layout.peopleinfo, null);  holder.callImg = (ImageView) convertView   .findViewById(R.id.callbtn);  holder.headImg = (ImageView) convertView   .findViewById(R.id.contactImage);  holder.peopleName = (TextView) convertView   .findViewById(R.id.peopleName);  holder.peopleNumber = (TextView) convertView   .findViewById(R.id.peopleNumber);  convertView.setTag(holder);  } else {  holder = (ViewHolder) convertView.getTag();  }  final String name = (String) listPeople.get(position).get(   "peopleName");  final String num = (String) listPeople.get(position).get(   "peopleNumber");  holder.peopleName.setText((String) listPeople.get(position).get(   "peopleName"));  holder.peopleNumber.setText((String) listPeople.get(position).get(   "peopleNumber"));  //  holder.headImg.setImageResource(R.drawable.ic_menu_contact);  if(listPeople.get(position).get("peoplePhoto") != null){  holder.headImg.setImageBitmap((Bitmap)listPeople.get(position).get(  "peoplePhoto"));  }  holder.callImg.setImageResource(R.drawable.ic_dial_action_call);  holder.callImg.setOnClickListener(new View.OnClickListener() {  public void onClick(View v) {  //处理Items中控件的触发事件  }  });  return convertView; } }/**应用BaseAdapter**/final MyAdapter myAdapter = new MyAdapter(this);  contacts.setAdapter(myAdapter);  contacts.setOnItemClickListener(new OnItemClickListener() {  @SuppressWarnings("unchecked")  public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,   long arg3) {   Map<String, Object> map = (Map<String, Object>) myAdapter.getItem(arg2);//此处需要注意，   String peopleNumber = String.valueOf(map.get("peopleNumber"));  }});