我是Android的菜鸟，我已经阅读了很多xamples，但到目前为止没有成功，所以基本上我希望我的listview利用baseadapter在我向下滚动时添加更多行，以及添加更多行的机制将是再次查询动态URL，现在实现查询的on scroll函数，但适配器生成一个新列表n丢弃旧的，这里是代码
public class Second extends Activity {
static final String Li_nk = "LinkName:";
static final String Image_name = "ImageName:";
// ListView list;
public final static String AUTH = "authentication";
static final String KEY_THUMB_URL = "thumb_image";
// JSONObject j2;
String wrd;
int counter = 01;
// ArrayList<HashMap<String,String>> mylist;
@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Intent i2 = getIntent();
wrd = i2.getStringExtra("entrd");
Log.v("keyis", wrd);
final Handler handler = new Handler();
Runnable runable = new Runnable() {
@Override
public void run() {
// call the function
LoadData();
// also call the same runnable
handler.postDelayed(this, 40000);
}
};
handler.postDelayed(runable, 10);
}
public void LoadData() {
JSONObject j2 = JSONfunctions
.getJSONfromURL("/webservice_search.php?keyword=" + wrd
+ "&format=json&pagenum=" + counter);
final ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
try {
JSONArray jray = j2.getJSONArray("listings");
for (int i = 0; i < jray.length(); i++) {
Log.v("state", "json data being read");
JSONObject j3 = jray.getJSONObject(i);
String first = j3.getString("listing");
Log.v("sublist", first);
JSONObject j4 = j3.getJSONObject("listing");
String sec = j4.getString("links");
int maxLength = (sec.length() < 30) ? sec.length() : 27;
sec.substring(0, maxLength);
String cutsec = sec.substring(0, maxLength);
Log.v("links are", cutsec);
String img = j4.getString("image_name");
Log.v("image name is ", img);
// Uri
// dimg=Uri.parse("http://zeesms.info/android_app_images/Koala.jpg");
HashMap<String, String> map = new HashMap<String, String>();
map.put("Id", String.valueOf(i));
map.put(Li_nk, cutsec);
map.put(Image_name, j4.getString("image_name"));
map.put(KEY_THUMB_URL, "http://zeesms.info/android_app_images/"
+ img);
mylist.add(map);
}
} catch (JSONException e) {
Log.e("loG_tag", "Error parsing" + e.toString());
}
final LazyAdapter adapter = new LazyAdapter(this, mylist);
adapter.notifyDataSetChanged();
View footerView = ((LayoutInflater) this
.getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(
R.layout.footer, null, false);
ListView list = (ListView) findViewById(R.id.lv1);
list.setEmptyView(findViewById(R.id.empty));
list.addFooterView(footerView);
list.setAdapter(adapter);
list.setItemsCanFocus(false);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// Toast.makeText(getApplicationContext(),"Click ListItem Number "
// + position, Toast.LENGTH_LONG).show();
Intent myIntent = new Intent(Intent.ACTION_VIEW, Uri
.parse("http://www.google.com/"));
startActivity(myIntent);
}
});
list.setOnScrollListener(new OnScrollListener() {
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
// what is the bottom iten that is visible
int lastInScreen = firstVisibleItem + visibleItemCount;
if (lastInScreen == totalItemCount) {
counter++;
LoadData();
adapter.notifyDataSetChanged();
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
});
}
我的适配器类的代码是
public class LazyAdapter extends BaseAdapter {
private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader;
//int count=5;
public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
activity = a;
data=d;
Collections.reverse(d);
inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
imageLoader=new ImageLoader(activity.getApplicationContext());
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return data.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
/*position=1;
position=2;
position=3;
position=4;
position=5;*/
View vi=convertView;
if(convertView==null)
vi = inflater.inflate(R.layout.custom_row_view1, null);
TextView title = (TextView)vi.findViewById(R.id.linkname); // merchnts name
TextView artist = (TextView)vi.findViewById(R.id.imagename); // address
//TextView duration = (TextView)vi.findViewById(R.id); // distance
ImageView thumb_image=(ImageView)vi.findViewById(R.id.mClogo); // logo
HashMap<String, String> jsn = new HashMap<String, String>();
jsn = data.get(position);
// Setting all values in listview
title.setText(jsn.get(Second.Li_nk));
artist.setText(jsn.get(Second.Image_name));
//duration.setText(song.get(CustomizedListView.KEY_DURATION));
imageLoader.DisplayImage(jsn.get(Second.KEY_THUMB_URL), thumb_image);
return vi;
}
现在新列表附加旧列表的最简单方法是什么，还是滚动后会添加更多视图的其他方式？
答案 0 :(得分：1)
您可以为列表视图添加onscrollchange侦听器，当最后一个位置可见时，向其添加元素，并相应地增加列表视图的大小。
在lazyadapter中添加一个方法说
setData(HashMap<string,string> newdata){
this.data = newdata;
}
每次点击webservice并获得响应都会将数据附加到newConcretehashmap并调用上面的方法。通过这个，你将只获得hashmap中更新的newData。然后只需调用notifydatasetchanged（）;并且列表将更新。