Set margin on RecyclerView programmatically

Question

I need to set the top margin on a RecyclerView programmatically, but I get this exception:

java.lang.RuntimeException: Unable to resume activity java.lang.ClassCastException: android.view.ViewGroup$LayoutParams cannot be cast to android.support.v7.widget.RecyclerView$LayoutParams

Here is my code:

RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams)recyclerView.getLayoutParams();
int marginTopDp = (int)getResources().getDimension(R.dimen.margin);
int marginTopPx = (int) (marginTopDp * getResources().getDisplayMetrics().density + 0.5f);
layoutParams.setMargins(0, marginTopPx, 0, 0);
recyclerView.setLayoutParams(layoutParams);

If I use ViewGroup.LayoutParams layoutParams = recyclerView.getLayoutParamsas a stack trace, I can no longer call setMargin, because this method does not exist for ViewGroup.LayoutParams.

Any help would be appreciated.

Answer 1

Try it. You can refer to this for more information.

ViewGroup.MarginLayoutParams marginLayoutParams = new ViewGroup.MarginLayoutParams(mRecyclerView.getLayoutParams());
marginLayoutParams.setMargins(0, 10, 0, 10);
mRecyclerView.setLayoutParams(marginLayoutParams);

Answer 2

You need a new MargingLayoutParams object

    final FrameLayout.MarginLayoutParams marginLayoutParams = new      
                      FrameLayout.MarginLayoutParams(rvContacts.getLayoutParams());
    marginLayoutParams.leftMargin = left;
    marginLayoutParams.topMargin = top;
    marginLayoutParams.rightMargin = right;
    marginLayoutParams.bottomMargin = bottom;

    recyclerView.setLayoutParams(marginLayoutParams);
    recyclerView.requestLayout();