我有一个问题，我的recyclerview在最后添加了新项目，而我想在用户刷新时在顶部添加最新项目。我一直在网上喋喋不休，它基本上归结为添加setreverseLayout或setStackFromEnd。这会产生其他复杂情况，例如回收者视图不会滚动到最新项目的顶部。
然后我想到了可能按照特定值排序我的数据列表然后它应该按照我想要的方式返回它。可以这样做，它会解决我的问题吗？我想按值adopt_rownum desc。
对其进行排序我的自定义适配器
package com.example.admin.paws;
import android.content.Context;
import android.content.Intent;
import android.graphics.Typeface;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.bumptech.glide.Glide;
import java.util.List;
/**
* Created by admin on 9/16/2016.
*/
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
public Context context;
public List<MyData> my_data;
public CustomAdapter(Context context, List<MyData> my_data) {
this.context = context;
this.my_data = my_data;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardnew,parent,false);
return new ViewHolder(itemView);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
String name = my_data.get(position).getName();
String age = my_data.get(position).getAge();
String gender = my_data.get(position).getGender();
String SubstAge = age.substring(0,age.indexOf("(") -1);
String NameAgeGender = name + ", " + SubstAge + ", " + gender;
holder.about.setText(my_data.get(position).getAbout());
holder.NameAgeGender.setText(NameAgeGender);
Glide.with(context).load(my_data.get(position).getPhoto_path()).into(holder.photo_path);
//activity_card_details vars
// final String about = my_data.get(position).getAbout();
final String adoptId = my_data.get(position).getId()+"";
final String photo_path_dtls = my_data.get(position).getPhoto_path();
final String listedDate = my_data.get(position).getDatetime_listed();
final String status = my_data.get(position).getStatus();
final String breed = my_data.get(position).getBreed();
final String source = my_data.get(position).getSource();
final String contact_info = my_data.get(position).getContact_info();
final String suburb = my_data.get(position).getSuburb();
final String city = my_data.get(position).getCity();
final String province = my_data.get(position).getProvince();
final String concat_location = suburb + ", " + city + ", " + province;
final String viewCounter = my_data.get(position).getViewCounter()+"";
//When click on photo
holder.photo_path.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(context,CardDetailsActivity.class);
intent.putExtra("listedDate",listedDate);
intent.putExtra("adoptId",adoptId);
// intent.putExtra("about",about);
intent.putExtra("status",status);
intent.putExtra("breed",breed);
intent.putExtra("source",source);
intent.putExtra("contactinfo",contact_info);
intent.putExtra("location",concat_location);
intent.putExtra("photo_path_dtls",photo_path_dtls);
intent.putExtra("viewCounter",viewCounter);
context.startActivity(intent);
}
});
}
@Override
public int getItemCount() {
return my_data.size();
}
public class ViewHolder extends RecyclerView.ViewHolder
{
public TextView NameAgeGender;
public ImageView photo_path;
public TextView about;
private ViewHolder(View itemView) {
super(itemView);
about = (TextView) itemView.findViewById(R.id.about);
NameAgeGender = (TextView) itemView.findViewById(R.id.tvNameAgeGender);
// NameAgeGender.setTextColor(Color.parseColor("#9C9393"));
Typeface typeface = Typeface.createFromAsset(context.getAssets(), "fonts/Lato-Medium.ttf");
NameAgeGender.setTypeface(typeface);
//NameAgeGender.setBackgroundColor(Color.parseColor("#F35959"));
photo_path = (ImageView) itemView.findViewById(R.id.photo_path);
}
}
}
我的数据列表
package com.example.admin.paws;
public class MyData {
//the must be in the same order of the select column order
public int adopt_rownum
,viewCounter
,adopt_id;
private String
name
,type
,breed
,age
,gender
,size
,about
,photo_path
,source
,contact_info
,suburb
,city
,province
,datetime_listed
,status;
public MyData(
int adopt_rownum,
int viewCounter,
int adopt_id,
String name,
String type,
String breed,
String age,
String gender,
String size,
String about,
String photo_path,
String source,
String contact_info,
String suburb,
String city,
String province,
String datetime_listed,
String status)
{
this.adopt_rownum = adopt_rownum;
this.viewCounter = viewCounter;
this.adopt_id = adopt_id;
this.name = name;
this.type = type;
this.breed = breed;
this.age = age;
this.gender = gender;
this.size = size;
this.about = about;
this.photo_path = photo_path;
this.source = source;
this.contact_info = contact_info;
this.suburb = suburb;
this.city = city;
this.province = province;
this.datetime_listed = datetime_listed;
this.status = status;
}
//adopt_rownum used for filtering the records.
public int getAdopt_rownum() {
return adopt_rownum;
}
//viewcounter
public int getViewCounter() {
return viewCounter;
}
//adopt_id
public int getId() {
return adopt_id;
}
public void setId(int adopt_id) {
this.adopt_id = adopt_id;
}
//name
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//type
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
//breed
public String getBreed() {
return breed;
}
public void setBreed(String breed) {
this.breed = breed;
}
//age
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
//gender
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.age = gender;
}
//size
public String getSize() {
return size;
}
public void setSize(String size) {
this.size = size;
}
//about
public String getAbout() {
return about;
}
public void setAbout(String about) {
this.about = about;
}
//photo path
public String getPhoto_path() {
return photo_path;
}
public void setPhoto_path(String photo_path) {
this.photo_path = photo_path;
}
//source
public String getSource() {
return source;
}
public void setSource(String source) {
this.source = source;
}
//contact_info
public String getContact_info() {
return contact_info;
}
public void setContact_info(String contact_info) {
this.contact_info = contact_info;
}
//suburb
public String getSuburb() {
return suburb;
}
public void setSuburb(String suburb) {
this.contact_info = suburb;
}
//city
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
//province
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
//datetime_listed
public String getDatetime_listed() {
return datetime_listed;
}
public void setDatetime_listed(String datetime_listed) {
this.datetime_listed = datetime_listed;
}
//status
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
}
显示结果的片段。另一个问题是，在load_data_from_server的这个片段中，它给了我一个警告：“这个异步任务应该是静态的，否则可能会发生泄漏”。我不知道这意味着什么，因为我对JAVA完全不熟悉。
package com.example.admin.paws;
import android.app.Activity;
import android.content.Context;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link feedFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link feedFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class feedFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
public Activity FragActivity;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private List<MyData> data_list;
private CustomAdapter adapter;
RecyclerView recyclerView;
public String EndOfFeed;
private OnFragmentInteractionListener mListener;
public feedFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment fragment_feed.
*/
// TODO: Rename and change types and number of parameters
public static feedFragment newInstance(String param1, String param2) {
feedFragment fragment = new feedFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
setHasOptionsMenu(true);
View rootView = inflater.inflate(R.layout.fragment_feed, container, false);
final GridLayoutManager gridLayoutManager;
final SwipeRefreshLayout swipeRefreshLayout = rootView.findViewById(R.id.feedRefresh);
TextView tvEndOfFeed = rootView.findViewById(R.id.tvEndOfFeed);
tvEndOfFeed.setText(EndOfFeed);
//recycler view
recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
data_list = new ArrayList<>();
load_data_from_server(0, "getFeed.php");
gridLayoutManager = new GridLayoutManager(getActivity(), 1); //2 nr of cards next to each other
recyclerView.setLayoutManager(gridLayoutManager);
//gridLayoutManager.setReverseLayout(true);
adapter = new CustomAdapter(getActivity(), data_list);
recyclerView.setAdapter(adapter);
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if (gridLayoutManager.findLastCompletelyVisibleItemPosition() == data_list.size() - 1) {
load_data_from_server(data_list.get(data_list.size() - 1).getAdopt_rownum(), "getFeed.php");
}
}
});
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
//this works but issue with the ordering of the adoptrownum
load_data_from_server(data_list.get(data_list.size() -1).getAdopt_rownum(), "refreshFeed.php");
swipeRefreshLayout.setRefreshing(false);
}
});
return rootView;
}
private void load_data_from_server(final int adopt_id, final String phpScript) {
AsyncTask<Integer,Void,Void> task = new AsyncTask<Integer, Void, Void>() {
@Override
protected Void doInBackground(Integer... integers) {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("http://10.0.2.2/app_scripts/"+phpScript+"?adopt_rownum="+integers[0])
.build();
try {
Response response = client.newCall(request).execute();
JSONArray array = new JSONArray(response.body().string());
for (int i=0; i<array.length(); i++){
JSONObject object = array.getJSONObject(i);
MyData data = new MyData(
object.getInt("ADOPT_ROWNUM"),
object.getInt("VIEWCOUNTER"),
object.getInt("ADOPT_ID"),
object.getString("NAME"),
object.getString("TYPE"),
object.getString("BREED"),
object.getString("AGE"),
object.getString("GENDER"),
object.getString("SIZE"),
object.getString("ABOUT"),
object.getString("PHOTO_PATH"),
object.getString("SOURCE"),
object.getString("CONTACT_INFO"),
object.getString("SUBURB"),
object.getString("CITY"),
object.getString("PROVINCE"),
object.getString("DATETIME_LISTED"),
object.getString("STATUS")
);
data_list.add(data);
}
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
System.out.println("End of content"+e);
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
adapter.notifyDataSetChanged();
}
};
task.execute(adopt_id);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
我按照以下说明添加了比较器，但输出有点奇怪......
public class MyComparator implements Comparator<MyData > {
@Override
public int compare(final MyData o1, final MyData o2) {
Log.d("APP", "compare Starting... ");
Integer val1 = o1.getAdopt_rownum();
Log.d("APP", "compare val1... "+val1);
Integer val2 = o2.getAdopt_rownum();
Log.d("APP", "compare val1... "+val2);
Log.d("APP", "compare val1 and val2 ="+val1.compareTo(val2));
return val1.compareTo(val2);
}
}
output
compare Starting...
compare val1... 2
compare val2... 1
compare val1 and val2 =1
...
compare Starting...
compare val1... 14
compare val2... 15
compare val2 and val2 =1
以下是我在片段中实现它的方法
private void load_data_from_server(final int adopt_id, final String phpScript) {
AsyncTask<Integer,Void,Void> task = new AsyncTask<Integer, Void, Void>() {
@Override
protected Void doInBackground(Integer... integers) {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("http://10.0.2.2/app_scripts/"+phpScript+"?adopt_rownum="+integers[0])
.build();
try {
Response response = client.newCall(request).execute();
JSONArray array = new JSONArray(response.body().string());
for (int i=0; i<array.length(); i++){
JSONObject object = array.getJSONObject(i);
MyData data = new MyData(
object.getInt("ADOPT_ROWNUM"),
object.getInt("VIEWCOUNTER"),
object.getInt("ADOPT_ID"),
object.getString("NAME"),
object.getString("TYPE"),
object.getString("BREED"),
object.getString("AGE"),
object.getString("GENDER"),
object.getString("SIZE"),
object.getString("ABOUT"),
object.getString("PHOTO_PATH"),
object.getString("SOURCE"),
object.getString("CONTACT_INFO"),
object.getString("SUBURB"),
object.getString("CITY"),
object.getString("PROVINCE"),
object.getString("DATETIME_LISTED"),
object.getString("STATUS")
);
data_list.add(data);
**Collections.sort(data_list,new MyComparator());**
}
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
//System.out.println("End of content"+e);
EndOfFeed = e+"";
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
adapter.notifyDataSetChanged();
}
};
task.execute(adopt_id);
}
答案 0 :(得分：1)
您可以使用以下代码按属性对列表进行排序：
Collections.sort(myList, new MyComparator());
public static class MyComparator implements Comparator<MyData > {
@Override
public int compare(final MyData o1, final MyData o2) {
return o1.getAdoptRownum().compareTo(o2.getAdoptRownum());
}
}
我通常在相关的POJO类中声明比较器。然后，只要您刷新数据，就可以致电Collections.sort。