无法将数据从 RecyclerView 适配器传递到 Viewpager 适配器

Question

我正在创建简单的图片库应用程序，其中图像显示在 RecyclerView 内的 MainActivity 上，单击 Any Image 它将带我们到 SlideActivity，我想在 ViewPager 上显示图像，然后我们滑动所有图像应该显示在查看页面。为了检索图像，我使用 Glide。图像在 RecyclerView 上加载非常好，但是当我单击任何图像时，我得到这个异常“java.lang.ArrayIndexOutOfBoundsException：长度=15；索引=-1”。 我知道有很多类似的问题我看到了所有的代码但没有理解所以最后决定问我正在粘贴代码的问题我到目前为止尝试过什么。任何建议或建议都会有所帮助，因为我独自工作，没有导师，我正在学习。谢谢！

错误：

java.lang.ArrayIndexOutOfBoundsException: length=15; index=-1
        at java.util.ArrayList.get(ArrayList.java:439)
        at com.starmoonsolutions.imagegallery.RecycleViewAdapter$ViewHolder$1.onClick(RecycleViewAdapter.java:63)
        at android.view.View.performClick(View.java:6256)
        at android.view.View$PerformClick.run(View.java:24697)
        at android.os.Handler.handleCallback(Handler.java:789)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6541)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

ImageUrl.java

public class ImageUrl {
    String imageUrl;

    public String getImageUrl() {
        return imageUrl;
    }

    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl;
    }
}

主活动：

public class MainActivity extends AppCompatActivity {

    private ImageView imageView;
    RecyclerView recyclerView;
    GridLayoutManager gridLayoutManager;
    ArrayList<ImageUrl> imageUrlList;

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

        imageView = findViewById(R.id.imageView);
        recyclerView = findViewById(R.id.recyclerView);
        gridLayoutManager = new GridLayoutManager(getApplicationContext(), 2);
        recyclerView.setLayoutManager(gridLayoutManager);

        imageUrlList = prepareData();
        RecycleViewAdapter galleryAdapter = new RecycleViewAdapter(getApplicationContext(), imageUrlList);
        recyclerView.setAdapter(galleryAdapter);
    }
    private ArrayList prepareData(){
        // here you should give your image URLs and that can be a link from the Internet
        String imageUrls[] = {
                "https://images.pexels.com/photos/358457/pexels-photo-358457.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260",
                "https://images.pexels.com/photos/934964/pexels-photo-934964.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/1202887/pexels-photo-1202887.jpeg?auto=compress&cs=tinysrgb&h=650&w=940",
                "https://images.pexels.com/photos/337909/pexels-photo-337909.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/894443/pexels-photo-894443.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/951325/pexels-photo-951325.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/1534411/pexels-photo-1534411.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/266436/pexels-photo-266436.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/1894350/pexels-photo-1894350.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/87009/earth-soil-creep-moon-lunar-surface-87009.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/1820563/pexels-photo-1820563.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940",
                "https://images.pexels.com/photos/1274260/pexels-photo-1274260.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940"
        };
        imageUrlList = new ArrayList<>();
        for (int i = 0; i < imageUrls.length; i++) {
            ImageUrl imageUrl = new ImageUrl();
            imageUrl.setImageUrl(imageUrls[i]);
            imageUrlList.add(imageUrl);
        }
        Log.d("MainActivity", "List count: " + imageUrlList.size());
        return  imageUrlList;
    }
}

RecyclerViewAdapter：

    public class RecycleViewAdapter extends RecyclerView.Adapter<RecycleViewAdapter.ViewHolder>{

        private ArrayList<ImageUrl> imageUrls;
        private Context context;

        public RecycleViewAdapter(Context context, ArrayList<ImageUrl> imageUrls) {
            this.imageUrls = imageUrls;
            this.context = context;
        }

        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.image_layout, viewGroup, false);
            return new ViewHolder(view);
        }

        /**
         * gets the image url from adapter and passes to Glide API to load the image
         *
         * @param viewHolder
         * @param i
         */
        @Override
        public void onBindViewHolder(@NonNull ViewHolder viewHolder, int i) {
            Glide.with(context).load(imageUrls.get(i).getImageUrl()).into(viewHolder.img);
        }

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

        public class ViewHolder extends RecyclerView.ViewHolder{

            RecyclerView recyclerView;
            ImageView img;

            public ViewHolder(@NonNull final View itemView) {
                super(itemView);
                img = itemView.findViewById(R.id.imageView);
                recyclerView = itemView.findViewById(R.id.recyclerView);
                final int pos = getAdapterPosition();
                itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent(context, SlideActivity.class);
error point here->      intent.putExtra("image", String.valueOf(imageUrls.get(pos).getImageUrl())); <- error point here 
                        intent.putExtra("position", pos);
                        intent.putExtra("list", imageUrls.get(pos).imageUrl);
                        context.startActivity(intent);
                    }
                });
            }
        }
    }

SlideActivity(ViewPager)：

public class SlideActivity extends AppCompatActivity {
    private ViewPager viewPager;
    private Context context = SlideActivity.this;
    private ViewPagerAdapter adapter;
    private ArrayList<String> list;
    String image;
    private int position;

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

        viewPager = findViewById(R.id.viewPager);
        getIntentInfo();

        adapter = new ViewPagerAdapter(list,context);
        viewPager.setAdapter(adapter);
        viewPager.setCurrentItem((position));
    }

    private void getIntentInfo() {
        image = getIntent().getStringExtra("image");
        list  = getIntent().getStringArrayListExtra("list");
        position = getIntent().getIntExtra("position",0);
    }
}

ViewPagerAdapter：

public class ViewPagerAdapter extends PagerAdapter {
    private ArrayList<String> imageUrls;
    private android.content.Context context;
    private LayoutInflater inflater;
    private ImageView wallpaper;

    public ViewPagerAdapter() {

    }

    public ViewPagerAdapter(ArrayList<String> imageUrls, android.content.Context context) {
        this.imageUrls = imageUrls;
        this.context = context;
    }

    @Override
    public int getCount() {
        return imageUrls.size();
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
        return view.equals(o);
    }

    @NonNull
    @Override
    public Object instantiateItem(@NonNull final ViewGroup container, final int position) {

        inflater = LayoutInflater.from(container.getContext());
        View view = inflater.inflate(R.layout.pager_item, container, false);
        wallpaper = view.findViewById(R.id.walpaperImage);
        Glide.with(context).asBitmap().load(imageUrls.get(position)).into(wallpaper);
        container.addView(view, 0);
        return view;
    }

    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView((View) object);
    }
}

Answer 1

问题实际上在于获取适配器位置。

public ViewHolder(@NonNull final View itemView) {
                super(itemView);
                img = itemView.findViewById(R.id.imageView);
                recyclerView = itemView.findViewById(R.id.recyclerView);

                // remove the below line
                //final int pos = getAdapterPosition();

                itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent(context, SlideActivity.class);

                        // you need to freshly get the adapter position here.
                        int pos = getAdapterPosition();

error point here->      intent.putExtra("image", String.valueOf(imageUrls.get(pos).getImageUrl())); <- error point here 
                        intent.putExtra("position", pos);
                        intent.putExtra("list", imageUrls.get(pos).imageUrl);
                        context.startActivity(intent);
                    }
                });
            }

由于 ViewHolder 被回收，适配器位置可能会发生变化，因此您需要在点击侦听器中获取最新的适配器位置。

关于 Bundle 数据，传递 'String' 类型的 URL 列表而不是自定义对象，

public void onClick(View v) { 
Intent intent = new Intent(context, SlideActivity.class); 
error point here-> intent.putExtra("image", String.valueOf(imageUrls.get(pos).getImageUrl())); <- error point here 
intent.putExtra("position", pos); 

// imageUrls is of type ArrayList<String>
intent.putStringArrayListExtra("list", imageUrls);

context.startActivity(intent); }

或者使用 Parcelable library 序列化自定义对象。