无法为 RecyclerView 的 DividerItemDecoration 设置自定义 Drawable

Question

I have a RecyclerView displaying items horizontally and I want to add spacing between each items(but not at the start or end). I found this and also looked at the example from the official docs and even though I have declared the variable using var I get the following error:

I have configured my recycler view as follows:

myRecyclerView.apply {
  layoutManager = myLayoutManager
  adapter = myAdapter(data)
  addItemDecoration(divider)
}

It compiles and runs when I remove the line where I set my custom drawable. Why am I getting this error and how do you set a custom drawable?

Answer 1

正如CommonsWare 所指出的，它在将divider.drawable = drawableResource更改为divider.setDrawable(drawableResource) 。

Answer 2

It happens because in the DividerItemDecoration

public void setDrawable(@NonNull Drawable drawable) 
@Nullable public Drawable getDrawable() 

It means that the setter method accepts a Drawable while the getter return a Drawable? . Since they don't match you have to use the setter directly:

divider.setDrawable(..)

Answer 3

You can use the extension function below;

fun RecyclerView.setDecoration(@DrawableRes source: Int) {
val itemDecoration = DividerItemDecoration(this.context, DividerItemDecoration.VERTICAL)
ContextCompat.getDrawable(this.context, source)
    ?.let {
        itemDecoration.setDrawable(it)
        this.addItemDecoration(itemDecoration)
    }

}

Usage;

binding.rvFiles.setDecoration(R.drawable.separator_line)