Question

我的应用程序需要按顺序在列表循环视图中显示大量图像，每个项目视图都是一个图像视图，而项目视图的高度应该与所显示图像的高度完全相同，并且图像需要从网络加载。在加载图像后似乎无法更改项目视图的高度，发生NullPoint异常。有没有人遇到同样的问题？

以下是代码：

c = db.rawQuery("SELECT * FROM Your_tabename", null);
int i = c.getCount();

LogCat ：

recyclerView = (RecyclerView) findViewById(R.id.recycleView);
recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
recyclerView.setItemAnimator(new DefaultItemAnimator());
RecycleviewAdapter mRecycleviewAdapter = new RecycleviewAdapter(chData,chName,this);
recyclerView.setAdapter(mRecycleviewAdapter);

public class RecycleviewAdapter extends RecyclerView.Adapter<RecycleviewAdapter.MangaImageItemHolder> {

ChJs chJsonData;
String chName;
Context mContext;
int[] screenSize;
public RecycleviewAdapter(ChJs chJsonData, String chName, Context context){
    this.chJsonData = chJsonData;
    this.mContext = context;
    this.chName = chName;
    screenSize = Commons.getScreenSize(context);
}

@Override
public int getItemCount() {
    if(chJsonData!=null)
        return chJsonData.countOfPages();
    return 0;
}

@Override
public MangaImageItemHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    ImageView  mImageView = new ImageView(mContext);
    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);
    mImageView.setLayoutParams(params);
    return new MangaImageItemHolder(mImageView, this);
}

@Override
public void onBindViewHolder(final MangaImageItemHolder holder, int position) {


    String imageName = ImangaFileManager.imageName(chName,
            String.valueOf(position));
    final String localImagePath = ImangaFileManager.localImagePath(MangaReader.website,
            MangaReader.mangaName, imageName, mContext);

    ExecutorService executorService = MangaReader.Executor4Local();

    executorService.execute(new Runnable() {

        @Override
        public void run() {
            BitmapFactory.Options op = new BitmapFactory.Options();
            op.inPreferredConfig = Bitmap.Config.RGB_565;
            final Bitmap bm = BitmapFactory.decodeFile(localImagePath, op);

            ((SherlockActivity)mContext).runOnUiThread(new Runnable() {
                @Override
                public void run() {

                    int height =  screenSize[0]*bm.getHeight()/bm.getWidth();
                    RecyclerView.LayoutParams params = new RecyclerView.LayoutParams(RecyclerView.LayoutParams.MATCH_PARENT,height);
                    holder.itemView.setLayoutParams(params);
                    holder.mImageView.setImageBitmap(bm);

                }
            });

        }
    });

}

public static class MangaImageItemHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    private ImageView mImageView;

    public MangaImageItemHolder(View itemView, RecycleviewAdapter adapter) {
        super(itemView);
        itemView.setOnClickListener(this);
        mImageView = (ImageView) itemView;
    }

    @Override
    public void onClick(View v) {
    }


}
}

Answer 1

您可以通过在适配器中应用元素的屏幕比例高度来实现。返回值的函数：

    public static int containerHeight(MainActivity ba) {

      DisplayMetrics dm = new DisplayMetrics();
      ba.getWindowManager().getDefaultDisplay().getMetrics(dm);

      //get predefined value
      double ratio = Static.PIC_RATIO_VALUE; //ex 4.0

      return (int) (dm.heightPixels / ratio); 
  }

在适配器（onBindViewHolder模块）中，您需要具有以下内容：

        //set height in proportion to screen size
        int proportionalHeight UIUtil.containerHeight((MainActivity)mCntx);
        TableRow.LayoutParams params = new TableRow.LayoutParams(TableRow.LayoutParams.MATCH_PARENT, proportionalHeight); // (width, height)
        holder.container.setLayoutParams(params);

holder.container 是要应用高度逻辑的元素的根布局。

请参阅此blog post，其中详细了解如何实现此目标。

Answer 2

@Override
public void onBindViewHolder(final MyViewHolder holder, int position)      {
holder.imageviewlogo.post(new Runnable() {
@Override
public void run() {

        holder.imageviewlogo.getLayoutParams().height =     holder.linearlayoutDetails.getHeight();

        holder.imageviewlogo.getLayoutParams().width = holder.linearlayoutDetails.getHeight();

        holder.imageviewlogo.postInvalidate();
       }
    });
}

如何在异步加载图像后将项目视图的高度更改为Recycleview中图像的高度？

2 个答案: