错误 - 尝试在空对象引用上调用虚拟方法“int android.graphics.Bitmap.getHeight()”

如何解决错误 - 尝试在空对象引用上调用虚拟方法“int android.graphics.Bitmap.getHeight()”

当图像加载到回收器视图中时，我正在尝试将高度和宽度从固定更改为匹配父级或换行内容https://stackoverflow.com/a/67860281/15537898 这里是我正在尝试实现的答案，但在它给了我之后这个错误

尝试调用虚方法'int android.graphics.Bitmap.getHeight()' 在空对象引用上

Fragment_Search.java

ShapeableImageView siv;
    Bitmap bm;
    int height = bm.getHeight();
    int width = bm.getWidth();

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater,@Nullable ViewGroup container,@Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_search,container,false);
        requireActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
        postRecyclerView = view.findViewById(R.id.postRecyclerView);
        siv = view.findViewById(R.id.imageView);
        ViewGroup.LayoutParams params = siv.getLayoutParams();
        params.height = height;
        params.width = width;
        postRecyclerView.setLayoutManager(
                new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL)
        );
        params.height = ViewGroup.LayoutParams.WRAP_CONTENT;
        params.width = ViewGroup.LayoutParams.MATCH_PARENT;
        getData();
        mUploads = new ArrayList<>();
        postsAdapter = new PostAdapter_Search(getContext(),mUploads);
        postRecyclerView.setAdapter(postsAdapter);
        return view;
    }

解决方法

位图变量 (bm) 未初始化，即使您在 onCreateView 中初始化它，您的应用程序仍然会崩溃，因为您试图在 bm 变量初始化之前获取位图宽度和高度。你可以这样做

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,@Nullable ViewGroup container,@Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_search,container,false);
    
    bm = initialize_bitmap_here
    width = bm.getWidth()
    height = bm.getHeght()


    return view;
}