java - 无休止的滚动列表视图不起作用

Question

我正在开发一个应用程序。在我的应用程序中，我使用 listview 来显示来自 json 的数据。所有数据完美显示。但我想要的是，显示前 10 个对象，然后显示加载项，然后显示剩余的 10 个。我的 json 响应如下所示。

{
 "interestsent":
  [
   {
    "interestsent_user_id":369,
    "name":"abc",
    "profile_id":"686317",
    "image":"",
    },
    {
    "interestsent_user_id":369,
    "name":"def",
    "profile_id":"686318",
    "image":"",
    },
    {
    "interestsent_user_id":369,
    "name":"ghi",
    "profile_id":"686319",
    "image":"",
    },
     {
    "interestsent_user_id":369,
    "name":"jkl",
    "profile_id":"686320",
    "image":"",
    },
    {
    "interestsent_user_id":369,
    "name":"mno",
    "profile_id":"686321",
    "image":"",
    },
    {
    "interestsent_user_id":369,
    "name":"pqr",
    "profile_id":"686322",
    "image":"",
    },
    .................
    .................
 ]
 }

Interestsent.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    INTEREST_SENT_URL = "http://fshdfh.com/webservice/interestsent?version=apps&user_login_id=00";
    new GetData().execute("");
    listview = (ListView) findViewById(R.id.listview);
    Log.i("DATA", "page ::onCreate onCreate onCreate  ");
    mHandler = new Handler();
    listview.setOnScrollListener(new EndlessScrollListener() {
        @Override
        public void onLoadMore(int page, int totalItemsCount) {
            Log.i("DATA", "page :: " + page + " totalItemsCount :: "
                    + totalItemsCount);
            mProgressbar = new ProgressDialog(MainActivity.this);
            mProgressbar.setMessage("Loading...");
            mProgressbar.show();
            count++;
            if (count < maindata.size()) {
                if (adapter != null) {

                    if (!isLoadingMore) {
                        isLoadingMore = true;
                        mHandler.postDelayed(loadMoreRunnable, 1000);
                    }
                }
            }
        }
    });

}

Runnable loadMoreRunnable = new Runnable() {

    @Override
    public void run() {
        // TODO Auto-generated method stub
        if (count < maindata.size()) {
            if (adapter != null) { 
                adapter.addAll(maindata.get(count));
                mHandler.removeCallbacks(loadMoreRunnable);
                isLoadingMore = false;
                if (mProgressbar.isShowing())
                    mProgressbar.dismiss();
            }
        }
    }
};

static <T> ArrayList<ArrayList<T>> chunkList(List<T> list, final int L) {
    ArrayList<ArrayList<T>> parts = new ArrayList<ArrayList<T>>();
    final int N = list.size();
    for (int i = 0; i < N; i += L) {
        parts.add(new ArrayList<T>(list.subList(i, Math.min(N, i + L))));
    }
    return parts;
}
private ProgressDialog mProgressbar;
public class GetData extends AsyncTask<String, String, String> {
    ArrayList<Integer> data = new ArrayList<Integer>();


    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        mProgressbar = new ProgressDialog(MainActivity.this);
        mProgressbar.setMessage("Loading...");
        mProgressbar.show();
        super.onPreExecute();
    }

    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub
        ArrayList<ArrayList<Integer>> data = new ArrayList<ArrayList<Integer>>();
        ServiceHandler sh = new ServiceHandler();
        /*try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }*/
        /*for (int i = 0; i < 500; i++) {
            data.add(i);
        }

        return null;*/

        String jsonStr = sh.makeServiceCall(INTEREST_SENT_URL, ServiceHandler.GET);
        Log.d("Response: ", "> " + jsonStr);
        if (jsonStr != null) {
            try {
                JSONObject jsonObj = new JSONObject(jsonStr);
                // Getting JSON Array node
                interestsent = jsonObj.getJSONArray(INTEREST_SENT);
                // looping through All Contacts
                for (int i = 0; i < interestsent.length(); i++) {
                    JSONObject c = interestsent.getJSONObject(i);
                    // creating new HashMap
                   // HashMap<ArrayList<Integer> map = new  HashMap<Integer>();
                   HashMap<String, String> map = new HashMap<String, String>();
                    // adding each child node to HashMap key => value
                    map.put(INTEREST_USER_ID, c.getString(INTEREST_USER_ID));
                    map.put(INTEREST_SENT_NAME,c.getString(INTEREST_SENT_NAME));
                    map.put(INTEREST_SENT_PROFILE, c.getString(INTEREST_SENT_PROFILE));
                    map.put(INTEREST_SENT_IMAGE, c.getString(INTEREST_SENT_IMAGE));
                    map.put(INTEREST_SENT_CAST, c.getString(INTEREST_SENT_CAST));
                    map.put(INTEREST_SENT_AGE, c.getString(INTEREST_SENT_AGE)+" years");
                    map.put(INTEREST_SENT_LOCATION, c.getString(INTEREST_SENT_LOCATION));
                    // adding HashList to ArrayList
                    data.addAll(map);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        } else {
            Log.e("ServiceHandler", "Couldn't get any data from the url");
        }

        return data;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        maindata = chunkList(data, 50);
        Log.i("DATA", "maindata :: " + maindata.size());

        adapter = new CustomAdapterSent(maindata.get(count),
                MainActivity.this);
        listview.setAdapter(adapter);
        if (mProgressbar.isShowing())
            mProgressbar.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;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

EndlessScoolListener.java

 public abstract class EndlessScrollListener implements OnScrollListener {
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
// The current offset index of data you have loaded
private int currentPage = 0;
// The total number of items in the dataset after the last load
private int previousTotalItemCount = 0;
// True if we are still waiting for the last set of data to load.
private boolean loading = true;
// Sets the starting page index
private int startingPageIndex = 0;

public EndlessScrollListener() {
}

public EndlessScrollListener(int visibleThreshold) {
    this.visibleThreshold = visibleThreshold;
}

public EndlessScrollListener(int visibleThreshold, int startPage) {
    this.visibleThreshold = visibleThreshold;
    this.startingPageIndex = startPage;
    this.currentPage = startPage;
}

// This happens many times a second during a scroll, so be wary of the code you place here.
// We are given a few useful parameters to help us work out if we need to load some more data,
// but first we check if we are waiting for the previous load to finish.
@Override
public void onScroll(AbsListView view,int firstVisibleItem,int visibleItemCount,int totalItemCount) 
    {
    // If the total item count is zero and the previous isn't, assume the
    // list is invalidated and should be reset back to initial state
    if (totalItemCount < previousTotalItemCount) {
        this.currentPage = this.startingPageIndex;
        this.previousTotalItemCount = totalItemCount;
        if (totalItemCount == 0) { this.loading = true; } 
    }
    // If it’s still loading, we check to see if the dataset count has
    // changed, if so we conclude it has finished loading and update the current page
    // number and total item count.
    if (loading && (totalItemCount > previousTotalItemCount)) {
        loading = false;
        previousTotalItemCount = totalItemCount;
        currentPage++;
    }

    // If it isn’t currently loading, we check to see if we have breached
    // the visibleThreshold and need to reload more data.
    // If we do need to reload some more data, we execute onLoadMore to fetch the data.
    if (!loading && (totalItemCount - visibleItemCount)<=(firstVisibleItem + visibleThreshold)) {
        onLoadMore(currentPage + 1, totalItemCount);
        loading = true;
    }
}

// Defines the process for actually loading more data based on page
public abstract void onLoadMore(int page, int totalItemsCount);

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
    // Don't take any action on changed
}
}

CustomAdapterSent.java

公共类 CustomAdapterSent 扩展 BaseAdapter{

private ArrayList<Integer> mData = new ArrayList<Integer>();
private Context mContext;
private LayoutInflater inflater = null;

 private static final String TAG_NAME="name";
    private static final String TAG_PROFILE="profile_id";
    private static final String TAG_IMAGE="image";
    private static final String TAG_CAST="cast";
    private static final String TAG_AGE="age";
    private static final String TAG_LOCATION="location";

public CustomAdapterSent(ArrayList<Integer> mData, Context mContext) {
    this.mContext = mContext;
    this.mData = mData;
    inflater = (LayoutInflater) mContext
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

public void addAll(ArrayList<Integer> mmData) {
    this.mData.addAll(mmData);
    this.notifyDataSetChanged();
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return mData.size();
}

@Override
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return mData.get(arg0);
}

@Override
public long getItemId(int arg0) {
    // TODO Auto-generated method stub
    return 0;
}

class ViewHolder {
    public TextView txtView;
    TextView txtproname;
}

@Override
public View getView(int postion, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    View view = convertView;
    ViewHolder holder;
    if (view == null) {
        view = inflater.inflate(R.layout.row_layout, null);
        holder = new ViewHolder();
        ///holder.propic = (ImageView) convertView.findViewById(R.id.propicsent);
      //  holder.txtproname = (TextView) convertView.findViewById(R.id.txtpronameintsent);
        //holder.txtproid = (TextView) convertView.findViewById(R.id.txtproidsent);
        //holder.txtprofilecast = (TextView) convertView.findViewById(R.id.txtprofilecastintsent);
        //holder.txtprofileage = (TextView) convertView.findViewById(R.id.txtprofileageintsent);
      //  holder.txtprofileplace = (TextView) convertView.findViewById(R.id.txtprofileplaceintsent);
        holder.txtView = (TextView) view.findViewById(R.id.no_intsent);
        view.setTag(holder);
    } else {
        holder = (ViewHolder) view.getTag();
    }
    Log.i("DATA", "mData.get(postion) :: " + mData.get(postion));
    mData.get(postion);
    // holder.txtproname.setText(listData.get(position).get(TAG_NAME));
    holder.txtView.setText("Index :: " + Integer.getInteger(TAG_NAME));
    return view;
}
}

XML 文件：

   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
 android:id="@+id/relativemainss"
android:background="@drawable/backg"
 >

 <ListView android:id="@android:id/list"
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:dividerHeight="1dp">
 </ListView>
 <TextView 
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:layout_centerInParent="true"
    android:id="@+id/no_intsent"
    android:textColor="@android:color/black"
    android:background="@drawable/nomessaegborder" />

<Button 
      android:layout_height="wrap_content"
      android:layout_width="wrap_content"
      android:text="Load More"
      android:id="@+id/buttoloadmoreintsent"
     android:layout_below="@android:id/list" />


 </RelativeLayout>

Answer 1

第一次只显示 10 个项目ListView并在滚动时显示更多项目，请按照以下步骤操作：

第 1 步：创建一个chunkList分成ArrayList大小为 10 的部分的方法：

static <T> List<ArrayList<T>> chunkList(List<T> list, final int L) {
        List<ArrayList<T>> parts = new ArrayList<ArrayList<T>>();
        final int N = list.size();
        for (int i = 0; i < N; i += L) {
            parts.add(new ArrayList<T>(
                list.subList(i, Math.min(N, i + L)))
            );
        }
        return parts;
    }

第 2 步：创建ArrayList和显示当前部分的计数器：

    private boolean isLoadingMore=false;
    Handler mHandler = new Handler();
    List<ArrayList<HashMap<String,String>>> mainArrayList;
    private int count=0;

第 3步：在ListView 中onPostExecute中断并显示数据：result

protected void onPostExecute(ArrayList<HashMap<String,String>> result) {

              super.onPostExecute(result);
              // your code here...
               mainArrayList=chunkList(result,10);
               isLoadingMore=false;
               count=0;
               adapter = new CustomAdapterSent(Interestsent.this, 
                                            mainArrayList.get(count));
               setListAdapter(adapter);
        }

    }

第 4 步：在 Adapter 中创建 addAll 方法以在当前数据源中追加数据：

public void addAll(ArrayList<HashMap<String,String>> moreData){
   this.listData.addAll(moreData);
   this.notifyDataSetChanged();
}

第 5步：在onLoadMore ListView 中加载更多数据：

mHandler = new Handler();
 listview.setOnScrollListener(new EndlessScrollListener() {
        @Override
        public void onLoadMore(int page, int totalItemsCount) {
                 if(count<mainArrayList.size()-1)
                  {
                     if(adapter !=null){
            count++;                       
            if(!isLoadingMore){
                             isLoadingMore=true;
                             mHandler.postDelayed(loadMoreRunnable,1000); 
                          } 
                      }
                  } 
        }
        });
    }

     Runnable loadMoreRunnable = new Runnable() {

        @Override
        public void run() {
            // TODO Auto-generated method stub
         if(count<mainArrayList.size())
                   {
                     if(adapter !=null){
                      count++;                       
                      adapter.addAll(mainArrayList.get(count));
                      mHandler.removeCallbacks(loadMoreRunnable);
                      isLoadingMore=false;
                      }
                  } 
        }
    };

Answer 2

拥有一个 AdapterView（例如 ListView 或 GridView），当用户滚动项目时自动加载更多项目（又名无限滚动）。这是通过在用户超过剩余项目的阈值时触发对更多数据的请求来完成的。每个 AdapterView 都支持绑定到 OnScrollListener 事件，每当用户滚动浏览集合时就会触发这些事件。使用这个系统，我们可以定义一个基本的 EndlessScrollListener，它通过创建我们自己的扩展 OnScrollListener 的类来支持大多数用例。

您可以在以下链接中找到更多相关信息：

Android中的无限滚动ListView

使用 AdapterView 进行无限滚动

无限滚动列表视图

在这个 SO 答案中显示了一种在列表视图中添加数据的更简单方法：Android Endless List

希望这可以帮助 ...