Android之Adapter的用法

1.AdapterBase文件，继承 BaseAdapter ，为的是添加setlist方法

public abstract class AdapterBase extends BaseAdapter {


private List mList;
private Context mContext;
private LayoutInflater mLayoutInflater;

public AdapterBase(Context pContext,List pList)
{
mContext = pContext;
mList = pList;
mLayoutInflater = LayoutInflater.from(mContext);
}

public LayoutInflater GetLayoutInflater()
{
return mLayoutInflater;
}

public Context GetContext()
{
return mContext;
}

public List GetList()
{
return mList;
}

public void SetList(List pList) {
mList = pList;
}

@Override
public int getCount() {
return mList.size();
}


@Override
public Object getItem(int pPosition) {
return mList.get(pPosition);
}


@Override
public long getItemId(int pPosition) {
return pPosition;
}



}

2.MyAdapter文件 覆盖getView()方法

public class MyAdapter extends AdapterBase {


public MyAdapter(Context pContext, List pList) {
super(pContext, pList);
// TODO Auto-generated constructor stub
}


private class Holder
{
ImageView ivUserIcon;
TextView tvUserName;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Holder _Holder;

if (convertView == null) {
convertView = GetLayoutInflater().inflate(R.layout.user_list_item, null); 

 //GetLayoutInflater()保证了这个layout是与MainActivity里的listView一致lv = (ListView) findViewById(R.id.listView1);

_Holder = new Holder();
_Holder.ivUserIcon = (ImageView) convertView.findViewById(R.id.ivUserIcon);
_Holder.tvUserName = (TextView) convertView.findViewById(R.id.tvUserName);
convertView.setTag(_Holder);
}
else {
_Holder = (Holder) convertView.getTag();
}

User _Info = (User) GetList().get(position);

_Holder.ivUserIcon.setImageResource(R.drawable.user_big_icon);
_Holder.tvUserName.setText(_Info.getName());

return convertView;
}


}
3.activity文件

public class MainActivity extends Activity {
ListView lv;
List<User> lsdata = new ArrayList<User>();
List lsdata2;
MyAdapter ad;
ProgressDialog d;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ad = new MyAdapter(this, lsdata);                         // 必须lsdata =new ArrayList<User>();传到UserAdapter里，否则会报空指针异常
lv = (ListView) findViewById(R.id.listView1);


lv.setAdapter(ad);
d = new ProgressDialog(MainActivity.this);
d.show();
new Thread(networkTask).start();
}


private List<User> getData() {


List<User> data = new ArrayList<User>();
data.add(new User("jimmy", "jimmy"));


return data;
}


Runnable networkTask = new Runnable() {


@Override
public void run() {
// TODO
// 在这里进行 http request.网络请求相关操作
boolean result = false;
try {
Thread.sleep(3000);
lsdata = getData();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Message msg = new Message();
Bundle data = new Bundle();
if (lsdata != null && lsdata.size() > 0)
data.putString("result", "1");
else
data.putString("result", "0");
msg.setData(data);
handler.sendMessage(msg);
}
};


Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
Bundle data = msg.getData();
String result = data.getString("result");


if (Integer.parseInt(result) == 1) {
updateListViewData();
} else {
Log.i("mylog", "请求结果为-->no user list" + result);
// DialogUtil.showDialog(MainActivity.this
// , "no user list", false);
}
Log.i("mylog", "请求结果为-->" + result);
// TODO
// UI界面的更新等相关操作
}
};


public void updateListViewData() {
ad.SetList(lsdata);                                 //必须重新设置list，没这一句下面那句就无用
ad.notifyDataSetChanged();                //好像用notifyDataSetInvalidated()也可以
d.dismiss();


}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}


}