android - 项目上的 Recyclerview 单击将图像设置为 Activity 中的另一个 ImageView

Question

我正在研究 Recyclerview，我想将图像设置为从 Recyclerview 的所选项目中居中显示

Error : You must pass in a non null View

这里我试图通过 Recyclerview 的 Onclick 方法将图像设置到位于 activity_set_back.xml 中的 imageview

我有:包含所有 URL 的 moviesList(ArrayList)我在点击时获得位置我唯一需要做的就是将该图像设置为 img_back(Imageview) 在此代码中显示

MoviesAdapter.class

this is my adapter

    public class MoviesAdapter extends RecyclerView.Adapter<MoviesAdapter.MyViewHolder> {

    String string_url;
    String clicked_url;
    private ArrayList<Image> moviesList;

    public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public ImageView img_backimage;
        public ImageView img_back;

        public MyViewHolder(View itemView) {
            super(itemView);
            img_backimage = (ImageView) itemView.findViewById(R.id.img_backimage);
            img_back =(ImageView) itemView.findViewById(R.id.img_edit_this);
            itemView.setOnClickListener(this);


        }

        @Override
        public void onClick(View view) {
            int position = getLayoutPosition(); // gets item position
            clicked_url= moviesList.get(position).getPath();
            Toast.makeText(view.getContext(),position+"",Toast.LENGTH_LONG).show();
            Glide.with(view.getContext()).load(clicked_url)
                    .diskCacheStrategy(DiskCacheStrategy.ALL)
                    .fitCenter()
                    .crossFade()
                    .into(img_back);
        }

    }

    public MoviesAdapter(ArrayList<Image> moviesList) {
        this.moviesList = moviesList;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View rootView = inflater.inflate(R.layout.image_list_row, parent, false);
        return new MyViewHolder(rootView);
    }

    @Override
    public void onBindViewHolder(final MyViewHolder holder, int position) {
        string_url= moviesList.get(position).getPath();
        Glide.with(holder.img_backimage.getContext()).load(string_url)
                .diskCacheStrategy(DiskCacheStrategy.ALL)
                .fitCenter()
                .crossFade()
                .into(holder.img_backimage);
    }
    @Override
    public int getItemCount() {
        return moviesList.size();
    }
}

image_list_row.xml

<?xml version="1.0" encoding="utf-8"?>


 <RelativeLayout
        android:id="@+id/rl_single_item"
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="?android:attr/selectableItemBackground"
        android:clickable="true"
        android:focusable="true"
        android:orientation="horizontal"
        android:paddingBottom="8dp"
        android:paddingLeft="4dp"
        android:paddingRight="4dp"
        android:paddingTop="6dp">


        <ImageView
            android:id="@+id/img_backimage"
            android:layout_width="wrap_content"
            android:layout_height="100dp"
            android:layout_centerInParent="true"
            android:scaleType="fitCenter"
            android:src="@drawable/background"/>

    </RelativeLayout>

activity_set_back.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.weblogicindia.paint.SetBackActivity">

    <RelativeLayout
        android:id="@+id/rl_Paint_Area_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/grid_view_container">

        <RelativeLayout
            android:id="@+id/rl_Paint_Area2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:gravity="center"
            >

            <ImageView
                android:id="@+id/img_edit_this"
                android:layout_centerInParent="true"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:adjustViewBounds="true"
                android:scaleType="fitCenter"
                android:src="@drawable/background"/>


        </RelativeLayout>

    </RelativeLayout>

    <RelativeLayout
        android:id="@+id/grid_view_container"
        android:layout_width="match_parent"
        android:layout_alignParentBottom="true"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    </RelativeLayout>
</RelativeLayout>

Answer 1

这里您的 imageview- img_edit_this 在您的 Activity 中而不是在 itemview 中。为了从适配器访问您 Activity 中的 ImageView ，您首先需要在适配器初始化期间将监听器从您的 Activity 传递到适配器。然后在您的适配器中使用此监听器来更改 Activity 中的 ImageView 。

首先创建一个这样的界面

public interface RecyclerImageClick {
void onCenterImageChange(String imagePath);
}

让你的 Activity 实现这个，例如

public class MembersList extends AppCompatActivity implements RecyclerImageClick

现在在activity中实现方法onCenterImageChange(String imagePath)

现在在初始化适配器时，像这样将此监听器与数组列表一起传递给它

data= new MoviesAdapter(ArrayList<Image> moviesList,this);

现在像这样改变你的适配器构造函数

private RecyclerImageClick listener;
public MoviesAdapter(ArrayList<Image> moviesList,RecyclerImageClick listener) {
        this.moviesList = moviesList;
        this.listener=listener;
    }

现在在适配器的 ImageView 中单击监听器调用 listener.onCenterImageChange(imagePath)

现在在您的 Activity 中，声明您的 imageview 并将其设置为从 adapter 传递的图像路径