照片未出现在 RecyclerView 中答案

【问题标题】：Photos not appearing in RecyclerView照片未出现在 RecyclerView 中
【发布时间】：2016-08-26 20:49:24
【问题描述】：

我正在尝试在回收站视图中添加带有标题的 flickr 图像，我遇到的问题是我想在循环中将图像及其标题传递给 FlickrPhoto 类（请查看上方以了解我是什么说 ) 如果你注意到这一行 photos.add(new FlickrPhoto(title,uri));你会看到它在后台任务的入队函数中的循环内，所以我认识到该行没有执行..但是当我在入队函数之后尝试它对我有用但当然只适用于一张图像因为，我我在循环之外。我尝试了很多解决方案，但都失败了

这是我的 PhotoListActivity

package com.example.karim.bluecrunch;

/**
 * Created by karim on 8/26/16.
 */
public class FlickrPhoto {
    String title , image ;
    public  FlickrPhoto(String title , String image )
    {
        this.image = image;
        this.title = title;
    }
}

这是我的 PhotosRecyclerViewAdapter

package com.example.karim.bluecrunch;
public class PhotosRecyclerViewAdapter extends RecyclerView.Adapter<PhotosRecyclerViewAdapter.PhotoViewHolder> {

    List<FlickrPhoto> photos = Collections.emptyList();
    Context context;
    LayoutInflater inflater;

    public PhotosRecyclerViewAdapter(Context context , List<FlickrPhoto> photos)
    {
        this.context = context;
        this.photos = photos;
        inflater = LayoutInflater.from(context);
    }

    @Override
    public PhotoViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View row = inflater.inflate(R.layout.single_row,parent,false);
        return new PhotoViewHolder(row);
    }

    @Override
    public void onBindViewHolder(PhotoViewHolder holder, int position) {
        FlickrPhoto photo = photos.get(position);
        holder.textView.setText(photo.title);
        Uri uri = Uri.parse(photo.image);
        Glide.with(context).load(uri).placeholder(R.drawable.image_placeholder).crossFade().into(holder.imageView);

    }

    @Override
    public int getItemCount() {
        return photos.size();
    }

    public class PhotoViewHolder extends RecyclerView.ViewHolder {
        private TextView textView;
        private ImageView imageView;

        public PhotoViewHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView.findViewById(R.id.photoTitle);
            imageView = (ImageView) itemView.findViewById(R.id.flickrPhoto);
        }



    }
}

这是我的 PhotosListActivity

package com.example.karim.bluecrunch;

public class PhotosListActivity extends AppCompatActivity {
    List<FlickrPhoto> photos ;
    ArrayList<String> photosTitles;
    ArrayList<String> photoURLS;
    String title;
    String uri;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_photos_list);

        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.photo_recycler_view);
        recyclerView.setLayoutManager(new GridLayoutManager(getApplicationContext(),2));
        PhotosRecyclerViewAdapter adapter = new PhotosRecyclerViewAdapter(this,getPhotos());
        recyclerView.setAdapter(adapter);
    }

    public List<FlickrPhoto> getPhotos()
    {

        photos = new ArrayList<>();

        final String API_KEY = "fdac2e9676991ac53b34651adab52518";
        final String METHOD = "flickr.photos.search";
        final String AUTH_TOKEN = "72157671978046542-6e266595ffed01f8";
        final String API_SIG = "58e08d365779a8f2e946a2b5320199e2";
        final String FORMAT = "json";
        final int CALL_BACK = 1;

        HandleRetrofit handleRetrofit = HandleRetrofit.retrofit.create(HandleRetrofit.class);
        Call<Photos> call = handleRetrofit.Photos(METHOD,API_KEY,FORMAT,CALL_BACK,AUTH_TOKEN,API_SIG);
        call.enqueue(new Callback<Photos>() {
            @Override
            public void onResponse(Call<Photos> call, Response<Photos> response) {
                Log.d("MainActivity", "Status Code = " + response.code());
                PhotosRetrofit photosRetrofit = response.body().photos;
                for (int i = 0; i < photosRetrofit.getPhoto().size(); i++) {
                    uri="https://farm"+photosRetrofit.getPhoto().get(i).getFarm()+".staticflickr.com/"+
                            photosRetrofit.getPhoto().get(i).getServer()+"/"+
                            photosRetrofit.getPhoto().get(i).getId()+"_" +
                            photosRetrofit.getPhoto().get(i).getSecret()+".jpg";

                    title= photosRetrofit.getPhoto().get(i).getTitle();

                    photos.add(new FlickrPhoto(title,uri));


                    Log.w(">>>>>>>>>>>","https://farm"+photosRetrofit.getPhoto().get(i).getFarm()+".staticflickr.com/"+
                            photosRetrofit.getPhoto().get(i).getServer()+"/"+
                            photosRetrofit.getPhoto().get(i).getId()+"_" +
                            photosRetrofit.getPhoto().get(i).getSecret()+".jpg");
                }

            }

            @Override
            public void onFailure(Call<Photos> call, Throwable t) {
                Toast.makeText(PhotosListActivity.this,"Error :"+t.getMessage(),Toast.LENGTH_LONG).show();
                Log.w("---___--- Error ",t.getMessage());
            }
        });
    /*    Log.w("Hello",uri.toString());
        Log.w("Hello",title.toString());*/
        photos.add(new FlickrPhoto("karim","https://farm9.staticflickr.com/8450/29141814932_a62977990d.jpg"));
        return photos;
    }
}

一切正常，但我的活动中这一行的主要问题

photos.add(new FlickrPhoto(title,uri));

我认为它不能在后台任务中完成，因为这条线

photos.add(new FlickrPhoto("karim","https://farm9.staticflickr.com/8450/29141814932_a62977990d.jpg"));

在入队功能之后工作正常，但我不知道如何做这样的技巧来解决这个问题。

编辑

请注意循环

for (int i = 0; i < photosRetrofit.getPhoto().size(); i++) 
{
uri="https://farm"... ;
title= ..;
 **photos.add(new FlickrPhoto(title,uri));**
 Log.w(">>>>>>>>>>>","https://farm"+photosRetrofit.getPhoto()‌.get(i).getFarm()+".‌staticflickr.com/"+p‌hotosRetrofit.getPho‌to().get(i).getServe‌r()+"/"+photosRetrof‌it.getPhoto().get(i)‌.getId()+"_" +photosRetrofit.getPhoto().get(i).getSecret()+".jpg");
 }

没有跳过，因为如果您尝试在循环中记录 title 或 uri，它将在 Logcat 中成功显示。主要问题是这行代码photos.add(new FlickrPhoto(title,uri)); 将数据“title 和 uri”传递给了 FlickrPhoto 类的构造函数，这个操作在 enqueue -> onResponse（后台任务）中，我不知道为什么它不起作用

将数据（图像和标题）加载到回收站视图中除外，但实际上什么也没发生，

我已经尝试了几件事

首先，在 PhotosListActivity 类中返回 photos() arrayList 之前，我尝试将固定数据传递给 FlickrPhoto 类的构造函数，它可以工作并将图像显示到回收器视图中

其次，我尝试将默认构造函数和 setter、标题和图像的 getter 添加到 FlickrPhoto 类，并在 PhotosListActivity 类的 OnCreate 函数上初始化它，然后在 enqueue 上使用我的 setter 和 getter，它可以工作并加载所有数据成功，但是当我尝试再次运行时，一切都消失了！ :( ，我不知道为什么

做setter和getter是这样的 FlickrPhoto.java 类

package com.example.karim.bluecrunch;

/**
 * Created by karim on 8/26/16.
 */
public class FlickrPhoto {
    String title , image ;
    public FlickrPhoto(){}
    public  FlickrPhoto(String title , String image )
    {
        this.image = image;
        this.title = title;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

}

和 PostListActivity 类

package com.example.karim.bluecrunch;

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;

import java.net.URI;
import java.util.ArrayList;
import java.util.List;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.http.Url;

public class PhotosListActivity extends AppCompatActivity {
    List<FlickrPhoto> photos ;
    ArrayList<String> photosTitles;
    ArrayList<String> photoURLS;
    FlickrPhoto flickrPhoto ;
    String title;
    String uri;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_photos_list);

        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.photo_recycler_view);
        recyclerView.setLayoutManager(new GridLayoutManager(this,2));
        PhotosRecyclerViewAdapter adapter = new PhotosRecyclerViewAdapter(this,getPhotos());
        recyclerView.setAdapter(adapter);

        flickrPhoto = new FlickrPhoto();



    }

    public List<FlickrPhoto> getPhotos()
    {

        photos = new ArrayList<>();

        final String API_KEY = "fdac2e9676991ac53b34651adab52518";
        final String METHOD = "flickr.photos.search";
        final String AUTH_TOKEN = "72157671978046542-6e266595ffed01f8";
        final String API_SIG = "58e08d365779a8f2e946a2b5320199e2";
        final String FORMAT = "json";
        final int CALL_BACK = 1;

        HandleRetrofit handleRetrofit = HandleRetrofit.retrofit.create(HandleRetrofit.class);
        Call<Photos> call = handleRetrofit.Photos(METHOD,API_KEY,FORMAT,CALL_BACK,AUTH_TOKEN,API_SIG);
        call.enqueue(new Callback<Photos>() {
            @Override
            public void onResponse(Call<Photos> call, Response<Photos> response) {
                Log.d("MainActivity", "Status Code = " + response.code());
                PhotosRetrofit photosRetrofit = response.body().photos;
                //photosRetrofit.getPhoto().size()
                for (int i = 0; i < photosRetrofit.getPhoto().size(); i++) {
                    uri="https://farm"+photosRetrofit.getPhoto().get(i).getFarm()+".staticflickr.com/"+
                            photosRetrofit.getPhoto().get(i).getServer()+"/"+
                            photosRetrofit.getPhoto().get(i).getId()+"_" +
                            photosRetrofit.getPhoto().get(i).getSecret()+".jpg";

                    title= photosRetrofit.getPhoto().get(i).getTitle();

                    flickrPhoto.setImage(uri);
                    flickrPhoto.setTitle(title);

                    photos.add(new FlickrPhoto(flickrPhoto.getTitle(),flickrPhoto.getImage()));


                    Log.w("++++++++++++",photosRetrofit.getPhoto().get(i).getTitle());

                    Log.w(">>>>>>>>>>>","https://farm"+photosRetrofit.getPhoto().get(i).getFarm()+".staticflickr.com/"+
                            photosRetrofit.getPhoto().get(i).getServer()+"/"+
                            photosRetrofit.getPhoto().get(i).getId()+"_" +
                            photosRetrofit.getPhoto().get(i).getSecret()+".jpg");



                }

            }

            @Override
            public void onFailure(Call<Photos> call, Throwable t) {
                Toast.makeText(PhotosListActivity.this,"Error :"+t.getMessage(),Toast.LENGTH_LONG).show();
                Log.w("---___--- Error ",t.getMessage());
            }
        });
    /*    Log.w("Hello",uri.toString());
        Log.w("Hello",title.toString());*/
        photos.add(new FlickrPhoto("karim","https://farm9.staticflickr.com/8450/29141814932_a62977990d.jpg"));
        return photos;
    }
}

【问题讨论】：

您遇到了什么问题？你想做什么你不知道该怎么做？
我正在尝试在回收站视图中添加带有标题的 flickr 图像，遇到的问题是我想在循环中将图像及其标题传递给 FlickrPhoto 类（请看上面看看我在说什么enqueue 函数它适用于我，但当然只适用于一张图像，因为我在循环之外。我尝试了很多解决方案，但都失败了
请使用这些详细信息编辑您的原始问题。如果明确显示您所指的循环将有所帮助，这样潜在的答案就不必花费额外的时间来搜索它。
听起来你需要确定为什么循环内的行不执行。 onResponse() 有没有被调用过？如果是，循环迭代多少次？
哦，抱歉循环没有跳过，因为如果您尝试在循环中记录标题或 uri，它将在 Logcat 中成功显示。主要问题是这行代码photos.add(new FlickrPhoto(title,uri));将数据“title和uri”传递给FlickrPhoto类的构造函数，这个操作在enqueue -> onResponse（后台任务）中，我不知道为什么它不起作用

标签： android json gson retrofit2 flickr

【解决方案1】：

问题是RecyclerView 在将元素添加到数组列表及其数据后不会自动更新。您需要在适配器上调用 notifyDataSetChanged() 来强制执行此更新。

【讨论】：