java - 在 RecyclerView 中仅选择一张图像

Question

我有一个RecyclerView.Adapter，其中有一些数组。

带有字符串的 ArrayList 和带有整数的 ArrayList。字符串就像 url，整数就是照片。

首次打开应用程序时，将选择第一个项目。我有另一种单击方法，可以使另一个项目成为选定状态，并且该方法有效，但问题是第一个项目保持选定状态，因此对于每个图像单击作为选定状态，我只想选择一个项目并采用颜色。

这是我的代码。

RecyclerView的适配器

public class ListViewAdapter extends RecyclerView.Adapter<ListViewAdapter.ViewHolder>{
    private int selectedItem;

    private ArrayList<Integer> mImages = new ArrayList<>();
    private ArrayList<String> mSearchUrl = new ArrayList<>();
    private Context mContext;

    public ListViewAdapter(ArrayList<Integer> images, ArrayList<String> SearchUrl, Context context) {
        mImages = images;
        mContext = context;
        mSearchUrl = SearchUrl;
    }
    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.s_engine_item, viewGroup, false);

        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder viewHolder, final int i) {
        selectedItem = 0;
        if (selectedItem == i) {
            viewHolder.image.setBackgroundColor(Color.parseColor("#30000000"));
        }
        Glide.with(mContext).load(mImages.get(i))
                .into(viewHolder.image);
        viewHolder.searchUrl.setText(mSearchUrl.get(i));

        viewHolder.image.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                viewHolder.image.setBackgroundColor(Color.parseColor("#30000000"));
                selectedItem = i;

            }
        });

    }

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

    public class ViewHolder extends RecyclerView.ViewHolder{

        ImageView image;
        TextView searchUrl;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            image = itemView.findViewById(R.id.ivEngine);
            searchUrl = itemView.findViewById(R.id.ivEngineText);
        }
    }
}

这是 MainActivity.class

public void intSearch() {
    mImages.add(R.drawable.s_bing);
    mSearchUrl.add("https://www.bing.com/search?q=");

    mImages.add(R.drawable.s_google);
    mSearchUrl.add("https://www.google.com/search?q=");

    mImages.add(R.drawable.s_yahoo);
    mSearchUrl.add("www.yahoo.com");

    mImages.add(R.drawable.amazon_white256);
    mSearchUrl.add("www.amazon.com");

    mImages.add(R.drawable.amazon_white256);
    mSearchUrl.add("www.amazon.com");

    mImages.add(R.drawable.amazon_white256);
    mSearchUrl.add("www.amazon.com");

    initRecyclerView();
}
private void initRecyclerView() {
    LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
    RecyclerView recyclerView = findViewById(R.id.lvEngines);
    recyclerView.setLayoutManager(layoutManager);
    ListViewAdapter adapter = new ListViewAdapter(mImages, mSearchUrl, this);
    recyclerView.setAdapter(adapter);
}

Answer 1

全局初始化您选择的项目

public class ListViewAdapter extends RecyclerView.Adapter<ListViewAdapter.ViewHolder>{
    private int selectedItem = 0;
    .....

然后，每当您单击新图像时，就会在 onBindViewHolder 内通知您的适配器最后选定的项目单元格中的更改。

   viewHolder.image.setOnClickListener(new View.OnClickListener() {
       @Override
            public void onClick(View v) {
                int previousSelectedItem = selectedItem;
                selectedItem = i;
                notifyItemChanged(previousSelectedItem);     

               viewHolder.image.setBackgroundColor(Color.parseColor("#30000000"));      
            }
        });