listview scrolldown加載更多視圖

Question

我是android的noob，我讀了很多xamples，但迄今爲止沒有成功，所以基本上我希望我向下滾動時使用baseadapter的listview添加更多行，並且添加更多行的機制將再次查詢動態URL，現在執行的滾動功能的查詢時，但適配器生成一個新的列表ñ丟棄舊人，這裏的代碼

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) { 
     } 

    }); 
} 

和我的適配器類的代碼是

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; 
} 

現在會是什麼一個最簡單的方式，無論是新的列表追加舊的，還是有任何其他方式，它會在滾動後添加更多的意見？

Answer 1

您可以爲列表視圖添加onscrollchange偵聽器，並在最後一個位置可見時向其添加元素，並相應地增加列表視圖的大小。

添加在lazyadapter一個方法說

setData(HashMap<string,string> newdata){ 
this.data = newdata; 
} 

每次你打的互聯網服務和得到的迴應將數據添加到newConcretehashmap並調用上面的方法。通過這個，你只會得到hashData中更新的newData。然後調用notifydatasetchanged（）;該列表將得到更新。