【发布时间】：2014-10-20 06:25:32
【问题描述】：
我有custom adapter，它使用从服务器获取的数据填充自定义listview。我想要的是检查adapter 是否为空，如果为空，则将数据附加到listview，否则用数据和notifyDataSetChanged 填充listview。我正在实施OnScrollListener 以从服务器加载更多数据。但是adapter 永远不会是空的，并且总是会调用notifyDataSetChanged。
我的列表活动
public class ListResultActivity extends Activity implements OnScrollListener{
private ArrayList<BusinessListData> businesses;
private ListView businessList;
private LayoutInflater layoutInflator;
private BusinessListIconTask imgFetcher;
BusinessListDataAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.businesslist);
this.businessList = (ListView) findViewById(R.id.lvBusinesslist);
this.adapter= new BusinessListDataAdapter(this,
this.imgFetcher, this.layoutInflator, this.businesses);
getData();
businessList.setOnScrollListener(this);
}
@Override
public Object onRetainNonConfigurationInstance() {
Object[] myStuff = new Object[2];
myStuff[0] = this.businesses;
myStuff[1] = this.imgFetcher;
return myStuff;
}
/**
* Bundle to hold refs to row items views.
*
*/
public static class MyViewHolder {
public TextView businessName, businessAddress, phoneNo;
public Button btnProfile;
public ImageView icon;
public BusinessListData business;
}
public void setBusinesses(ArrayList<BusinessListData> businesses) {
this.imgFetcher = new BusinessListIconTask(this);
this.layoutInflator = LayoutInflater.from(this);
this.businesses = businesses;
if(adapter !=null){
this.adapter.notifyDataSetChanged();
}else{
this.adapter= new BusinessListDataAdapter(this,
this.imgFetcher, this.layoutInflator, this.businesses);
businessList.setAdapter(adapter);
}
}
private void getData() {
// TODO Auto-generated method stub
Intent myIntent = getIntent();
// gets the arguments from previously created intent
String metroTxt = myIntent.getStringExtra("key");
String metroLoc = myIntent.getStringExtra("loc");
String metroId = myIntent.getStringExtra("qt");
BusinessListApiTask spTask = new BusinessListApiTask(
ListResultActivity.this);
try {
spTask.execute(metroTxt, metroLoc, metroId);
} catch (Exception e) {
spTask.cancel(true);
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
if (businessList.getLastVisiblePosition() == totalItemCount - 1) {
getData();
adapter.notifyDataSetChanged();
Log.d("test count", "abc"+totalItemCount);
}
}
}
从服务器获取数据并设置为适配器的类
public class BusinessListApiTask extends AsyncTask<String, Integer, String> {
private ProgressDialog progDialog;
private Context context;
private ListResultActivity activity;
private static final String debugTag = "sodhpuch";
HashMap<String, String> queryValues;
/**
* Construct a task
*
* @param activity
*/
public BusinessListApiTask(ListResultActivity activity) {
// TODO Auto-generated constructor stub
super();
this.activity = activity;
this.context = this.activity.getApplicationContext();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
progDialog = ProgressDialog.show(this.activity, "Search", this.context
.getResources().getString(R.string.looking_for_business), true,
false);
}
@Override
protected String doInBackground(String... params) {
try {
// Log.d(debugTag, "Background:" +
// Thread.currentThread().getName());
String result = BusinessListHelper.downloadFromServer(params);
// try {
//
// updateSQLite(result);
//
// } catch (Exception e) {
// return result;
// }
Log.d("result", result);
return result;
} catch (Exception e) {
return new String();
}
}
@Override
protected void onPostExecute(String result) {
ArrayList<BusinessListData> businessData = new ArrayList<BusinessListData>();
progDialog.dismiss();
try {
JSONObject respObj = new JSONObject(result);
int success = respObj.getInt("success");
Log.d("Success", "abc"+success);
if (success == 1) {
JSONArray tracks = respObj.getJSONArray("idioms");
for (int i = 0; i < tracks.length(); i++) {
JSONObject track = tracks.getJSONObject(i);
String businessName = track.getString("name");
String businessAddress = track.getString("address");
String phone = track.getString("phone");
String id = track.getString("id");
String deals_in = track.getString("deals_in");
businessData.add(new BusinessListData(businessName,
businessAddress, id, phone, deals_in));
}
} else {
Log.d("Success", "first"+success);
// Log.d(debugTag, "Background:" + result);
// DBController controller = new DBController(context);
// businessData = controller.getBusinessList();
return ;
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// }
this.activity.setBusinesses(businessData);
}
我的适配器
public class BusinessListDataAdapter extends BaseAdapter implements
OnClickListener {
private static final String debugTag = "BusinessListDataAdapter";
private ListResultActivity activity;
private BusinessListIconTask imgFetcher;
private LayoutInflater layoutInflater;
private ArrayList<BusinessListData> businesses;
BusinessListData business;
public BusinessListDataAdapter(ListResultActivity a,
BusinessListIconTask i, LayoutInflater l,
ArrayList<BusinessListData> data) {
this.activity = a;
this.imgFetcher = i;
this.layoutInflater = l;
this.businesses = data;
}
@Override
public int getCount() {
return this.businesses.size();
}
public void clear()
{
businesses.clear();
notifyDataSetChanged();
}
@Override
public boolean areAllItemsEnabled() {
return true;
}
@Override
public Object getItem(int arg0) {
return null;
}
@Override
public long getItemId(int pos) {
return pos;
}
@Override
public View getView(int pos, View convertView, ViewGroup parent) {
MyViewHolder holder;
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.trackrow, parent,
false);
holder = new MyViewHolder();
holder.businessName = (TextView) convertView
.findViewById(R.id.tvBusinessName);
holder.businessAddress = (TextView) convertView
.findViewById(R.id.tvAddress);
holder.phoneNo = (TextView) convertView.findViewById(R.id.tvPhone);
holder.icon = (ImageView) convertView.findViewById(R.id.album_icon);
holder.btnProfile = (Button) convertView
.findViewById(R.id.btnProfile);
holder.btnProfile.setTag(holder);
convertView.setTag(holder);
} else {
holder = (MyViewHolder) convertView.getTag();
}
convertView.setOnClickListener(this);
business= businesses.get(pos);
holder.business = business;
holder.businessName.setText(business.getName());
holder.businessAddress.setText(business.getAddress());
holder.phoneNo.setText(business.getPhone());
holder.btnProfile.setOnClickListener(this);
// if(track.getImageUrl() != null) {
// holder.icon.setTag(track.getImageUrl());
// Drawable dr = imgFetcher.loadImage(this, holder.icon);
// if(dr != null) {
// holder.icon.setImageDrawable(dr);
// }
// } else {
holder.icon.setImageResource(R.drawable.filler_icon);
// }
return convertView;
}
@Override
public void onClick(View v) {
String deals_in = business.getDeals().toString();
Log.d("name", deals_in);
MyViewHolder holder = (MyViewHolder) v.getTag();
if (v instanceof Button) {
Intent profile = new Intent(activity,
ProfileActivity.class);
profile.putExtra("deals_in", deals_in);
profile.putExtra("phone", holder.business.getPhone());
profile.putExtra("address", holder.business.getAddress());
profile.putExtra("name", holder.business.getName());
this.activity.startActivity(profile);
} else if (v instanceof View) {
Log.d("test","call testing");
Intent intent = new Intent(Intent.ACTION_CALL);
intent.setData(Uri.parse("tel:" +holder.business.getPhone()));
this.activity.startActivity(intent);
}
Log.d(debugTag, "OnClick pressed.");
}
}
【问题讨论】：
标签： android listview baseadapter custom-adapter onscrolllistener