notifyDataSetChanged（）使列表刷新並滾動跳回列表的頂部

Question

這是主要的類。當我向下滾動查看更多數據並調用適配器時，列表將刷新並滾動回滾到列表頂部。我試了兩天，但問題依然存在。

我想在滾動位置時列表的位置相同。

public class MainActivity extends AppCompatActivity { 

    private ProgressDialog pDialog; 

    ArrayList<String> home_youmay_filepath = new ArrayList<String>(); 


    ListView listViewyoumay; 

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

     pDialog = new ProgressDialog(MainActivity.this); 
     pDialog.setMessage("Please wait..."); 
     pDialog.setCancelable(false); 

     listViewyoumay = (ListView) findViewById(R.id.lvItems); 
     // Attach the listener to the AdapterView onCreate 
     listViewyoumay.setOnScrollListener(new EndlessScrollListener() { 
      @Override 
      public boolean onLoadMore(int page, int totalItemsCount) { 
       // Triggered only when new data needs to be appended to the list 
       // Add whatever code is needed to append new items to your AdapterView 
       youmaylike(page); 

       // or customLoadMoreDataFromApi(totalItemsCount); 
       return true; // ONLY if more data is actually being loaded; false otherwise. 

      } 
     }); 

     youmaylike(1); 


    } 

    private void showpDialog() { 
     if (!pDialog.isShowing()) 
      pDialog.show(); 
    } 

    private void hidepDialog() { 
     if (pDialog.isShowing()) 
      pDialog.dismiss(); 
    } 

    private void youmaylike(int a) { 

     showpDialog(); 

     Log.d("Starta", "Start" + a); 

     String url = "http://v2.picsdream.com/api/v1/galleries/abstract?page=" + a; 


     JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET, 
       url, null, new Response.Listener<JSONObject>() { 

        @Override 
        public void onResponse(JSONObject response) { 
         Log.d("cmsResponce", response.toString()); 

         try { 


          JSONObject cards = response.getJSONObject("cards"); 


          JSONArray data = cards.getJSONArray("data"); 

          for (int i = 0; i < data.length(); i++) { 

           JSONObject person = (JSONObject) data 
      .get(i); 


           String filepath = person.getString("filepath"); 


           home_youmay_filepath.add(filepath); 


          } 

          PhotofargmentAdapteryoumay adapter3 = new PhotofargmentAdapteryoumay(MainActivity.this, home_youmay_filepath); 
          listViewyoumay.setAdapter(adapter3); 
          adapter3.notifyDataSetChanged(); 


         } catch (JSONException e) { 
          e.printStackTrace(); 
          Toast.makeText(getApplicationContext(), 
            "Error: " + e.getMessage(), 
            Toast.LENGTH_LONG).show(); 
         } 
         hidepDialog(); 
        } 
       }, new Response.ErrorListener() { 

        @Override 
        public void onErrorResponse(VolleyError error) { 
         VolleyLog.d("LoginError", "Error: " + error.getMessage()); 
         Toast.makeText(getApplicationContext(), 
           error.getMessage(), Toast.LENGTH_SHORT).show(); 
         // hide the progress dialog 
         hidepDialog(); 
        } 
       }); 

     // Adding request to request queue 
     AppController.getInstance().addToRequestQueue(jsonObjReq); 
    } 


    public class PhotofargmentAdapteryoumay extends BaseAdapter { 


     ArrayList<String> home_youmay_filepath = new ArrayList<String>(); 



     private LayoutInflater layoutInflater; 
     Context context; 

     public PhotofargmentAdapteryoumay(Context Time_table, ArrayList<String> home_youmay_filepath) { 

      this.context = Time_table; 

      this.home_youmay_filepath = home_youmay_filepath; 


      layoutInflater = LayoutInflater.from(Time_table); 

     } 


     @Override 
     public int getCount() { 

      return home_youmay_filepath.size(); 
     } 

     @Override 
     public Object getItem(int position) { 
      return null; 
     } 

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

     @Override 
     public View getView(int position, View convertView, ViewGroup parent) { 
      ViewHolder holder; 
      if (convertView == null) { 
       convertView = layoutInflater.inflate(R.layout.photoadapter_layout, null); 
       holder = new ViewHolder(); 
       // holder.month = (TextView) convertView.findViewById(R.id.tvtext); 
       holder.img = (ImageView) convertView.findViewById(R.id.img_nature); 
       convertView.setTag(holder); 
      } else { 
       holder = (ViewHolder) convertView.getTag(); 
      } 
      // holder.month.setText(listData.get(position).getMonth()); 

      String image = home_youmay_filepath.get(position); 


      Log.d("Image", image); 


      try { 


       Picasso.with(context) 
        .load(image).noFade() 
        .into(holder.img); 

       //    ImageLoader imgLoader = new ImageLoader(HomeActivity.this); 
       // 
       //    imgLoader.DisplayImage(image, holder.img); 

      } catch (Exception e) { 
       e.printStackTrace(); 
      } 


      return convertView; 
     } 

     class ViewHolder { 
      // TextView month; 
      ImageView img; 
     } 
    } 


    public abstract class EndlessScrollListener implements AbsListView.OnScrollListener { 
     // The minimum number of items to have below your current scroll position 
     // before loading more. 
     private int visibleThreshold = 50; 
     // The current offset index of data you have loaded 
     private int currentPage = 1; 
     // The total number of items in the dataset after the last load 
     private int previousTotalItemCount = 50; 
     // 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 = 1; 

     public EndlessScrollListener() { 
     } 

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

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


     @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 && (firstVisibleItem + visibleItemCount + visibleThreshold) >= totalItemCount) { 
       loading = onLoadMore(currentPage + 1, totalItemCount); 
      } 
     } 

     // Defines the process for actually loading more data based on page 
     // Returns true if more data is being loaded; returns false if there is no more data to load. 
     public abstract boolean onLoadMore(int page, int totalItemsCount); 

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


} 

Answer 1

PhotofargmentAdapteryoumay adapter3 = new PhotofargmentAdapteryoumay(MainActivity.this, home_youmay_filepath); 
          listViewyoumay.setAdapter(adapter3); 

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