Question

我想在滚动回收器视图的同时从我的适配器加载更多内容。我实现了它，但它不起作用。我的Recycler视图工作正常，但滚动时我无法从列表中加载其余内容。目前我的代码中没有错误。但滚动时我无法加载更多项目。请帮忙。这是我的主要活动。

public class Contact_school extends AppCompatActivity implements SearchView.OnQueryTextListener {
private List<Contact> Listcontact = new ArrayList<>();
Contacts_Adapter cadapter;
private RecyclerView rv;
public String GET_CONTACTS = "http://xyzx.com/Publicpages_mob/brief_school_details";
  public  Contact contact;
public String school_id;
String tag_json_obj = "json_obj_req";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_contact_school);
    rv = (RecyclerView) findViewById(R.id.recycler_view);
    preparelist();
    cadapter = new Contacts_Adapter(Listcontact, rv);
    final LinearLayoutManager layoutManager = new     LinearLayoutManager(Contact_school.this);
    rv.setLayoutManager(layoutManager);
    rv.setItemAnimator(new DefaultItemAnimator());
    rv.setAdapter(cadapter);
    rv.setHasFixedSize(true);

   cadapter.setOnLoadMoreListener(new OnLoadMoreListener() {
       @Override
       public void onLoadMore() {

               Log.v(" KILILII ", "KITTTI");
      //add null , so the adapter will check view_type and show   progress bar at bottom
////                Listcontact.add(null);
////                cadapter.notifyItemInserted(Listcontact.size() -  1);

     //   remove progress item
////                Listcontact.remove(Listcontact.size() - 1);
////                cadapter.notifyItemRemoved(Listcontact.size());
//                //add items one by one
            int start = Listcontact.size();
            int end = start + 20;
            for (int i = start + 1; i <= end; i++) {
                Listcontact.add(contact);
                cadapter.notifyItemInserted(Listcontact.size());
            }
            cadapter.setLoaded();
                //or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
          }
    });
}

private void preparelist() {
    final StringRequest strReq = new StringRequest(Request.Method.POST, GET_CONTACTS,                new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            try {
                JSONObject jObj = new JSONObject(response);
                Log.e("RESPONSE TEST", "" + jObj);
                JSONArray jsonArray = jObj.getJSONArray("school_details");
                Log.e("RESPONSE ARRAY", "" + jsonArray);
                    Log.d("SUCESS ", response);
                 for (int i = 0; i < jsonArray.length(); i++) {
                     JSONObject jsonobject = jsonArray.getJSONObject(i);
                         contact = new Contact();
                         contact.setAddress(jsonobject.getString("school_address"));
                         contact.setRating(jsonobject.getString("school_rating"));
         Listcontact.add(contact);
                 }
                cadapter.notifyDataSetChanged();
            } catch (JSONException e) {
                e.printStackTrace();
            }

        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("Error", "Registration Error: " + error.getMessage());
            Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();
        }
    })
    {
        @Override
        protected Map<String, String> getParams() {
            // Posting params to register url
            Map<String, String> params = new HashMap<String, String>();
            return params;
        }
    };
    AppController.getInstance().addToRequestQueue(strReq, tag_json_obj);
}

这是我的适配器类

public class Contacts_Adapter extends RecyclerView.Adapter<Contacts_Adapter.MyViewHolder> {
private List<Contact> List1;

private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
public class MyViewHolder extends RecyclerView.ViewHolder {
      public TextView text_address,text_rating;

    public MyViewHolder(View view) {
        super(view);
        text_address = (TextView)view.findViewById(R.id.textaddress);

        text_rating = (TextView)view.findViewById(R.id.textrating);

    }
}
public Contacts_Adapter(List<Contact> List1,RecyclerView recyclerView)
{
  this.List1 = List1;
    if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
        final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView
                .getLayoutManager();
        recyclerView
                .addOnScrollListener(new RecyclerView.OnScrollListener() {
                    @Override
                    public void onScrolled(RecyclerView recyclerView,
                                           int dx, int dy) {
                        super.onScrolled(recyclerView, dx, dy);
                        totalItemCount = linearLayoutManager.getItemCount();
                        lastVisibleItem = linearLayoutManager
                                .findLastVisibleItemPosition();
                        if (!loading
                                && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                            // End has been reached
                            // Do something
                            if (onLoadMoreListener != null) {
                                onLoadMoreListener.onLoadMore();
                            }
                            loading = true;
                        }
                    }
                });
    }
}
@Override
public int getItemViewType(int position) {
    return List1.get(position) != null ? VIEW_ITEM : VIEW_PROG;
}
@Override
public Contacts_Adapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.recycler, parent, false);
    return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(MyViewHolder holder, final int position) {
    Contact c = List1.get(position);

    holder.text_rating.setText("Rating "+c.getRating());

    holder.text_address.setText(c.getAddress());

}
public void setLoaded() {
    loading = false;
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
    this.onLoadMoreListener = onLoadMoreListener;
}

这是我的模特课

public class Contact implements Serializable {
private static final long serialVersionUID = 1L;
   private String address,rating;
 public  Contact(){
}
public  Contact (String address, String rating){
    this.address = address;
    this.rating= rating;

}

 public String getAddress(){ return address;}
public  String getRating( ){return rating;}
public void setAddress(String ad){ this.address= ad;}
public void setRating(String ad){ this.rating= ad;}
}

我有这个界面

public interface OnLoadMoreListener {
void onLoadMore();
}

请帮助

Answer 1

您无需跟踪滚动条就知道何时搜索更多内容。

您可以从onBindViewHolder调用Volley请求，例如：

int itemsBeforeUpdate = 10;
public void onBindViewHolder(MyViewHolder holder, final int position) {
    Contact c = List1.get(position);
    holder.text_rating.setText("Rating "+c.getRating());
    holder.text_address.setText(c.getAddress());
    if(List1.size() - position <10){
     // Do your Volley Request, add response to the list and notify the adapter that the data changed

}


}

Answer 2

而不是在下面的块中调用OnLoadMoreListener

if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
       // End has been reached
       // Do something
       if (onLoadMoreListener != null) {
          onLoadMoreListener.onLoadMore();
       }
       loading = true;
}

只在此块中执行加载更多请求。像：

if (!loading&& totalItemCount <= (lastVisibleItem + visibleThreshold)) {
    // Load your volley request or load more request her
    loading = true;
}

然后通知适配器数据已被更改。

Answer 3

不是将值添加到活动类的列表中，而是通过将其添加到适配器类来尝试它。比如说在适配器中添加一个方法，如下所示。

public void addContact(Contact contact) {
list.add(contact);
notifyItemInserted(list.size());
}

而在活动而不是这个，

您的代码：

cadapter.setOnLoadMoreListener(new OnLoadMoreListener() {
       @Override
       public void onLoadMore() {

               Log.v(" KILILII ", "KITTTI");
      //add null , so the adapter will check view_type and show   progress bar at bottom
////                Listcontact.add(null);
////                cadapter.notifyItemInserted(Listcontact.size() -  1);

     //   remove progress item
////                Listcontact.remove(Listcontact.size() - 1);
////                cadapter.notifyItemRemoved(Listcontact.size());
//                //add items one by one
            int start = Listcontact.size();
            int end = start + 20;
            for (int i = start + 1; i <= end; i++) {
                Listcontact.add(contact);
                cadapter.notifyItemInserted(Listcontact.size());
            }
            cadapter.setLoaded();
                //or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
          }
    });

尝试：

cadapter.setOnLoadMoreListener(new OnLoadMoreListener() {
           @Override
           public void onLoadMore() {

                   Log.v(" KILILII ", "KITTTI");

                int start = Listcontact.size();
                int end = start + 20;
                for (int i = start + 1; i <= end; i++) {
                    cadapter.addContact(contact);
                }
                cadapter.setLoaded();
              }
        });

希望这有用：）

滚动的Android回收站视图

3 个答案: