在带有自定义第一个元素的RecyclerView中如何使第一个元素的高度等于屏幕的大小

public class CustomLayoutManager extends LinearLayoutManager {
    private Context mContext;

    public CustomLayoutManager(Context context) {
        super(context);
        mContext = context;
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
        super.onLayoutChildren(recycler, state);
        View firstChild = getChildAt(0);
        if (firstChild != null && getPosition(firstChild) == 0) {
            int screenHeight = getScreenHeight();
            firstChild.setLayoutParams(new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, screenHeight));
        }
    }

    private int getScreenHeight() {
        WindowManager windowManager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics displayMetrics = new DisplayMetrics();
        windowManager.getDefaultDisplay().getMetrics(displayMetrics);
        return displayMetrics.heightPixels;
    }
}

RecyclerView recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new CustomLayoutManager(this));