以编程方式在RecyclerView上设置保证金
我需要以编程方式在RecyclerView上设置上边距，但出现此异常:
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
这是我的代码:
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);
如果我按照堆栈跟踪的建议使用ViewGroup.LayoutParams layoutParams = recyclerView.getLayoutParams，我将无法再调用setMargin，因为ViewGroup.LayoutParams不存在该方法.
If I use the ViewGroup.LayoutParams layoutParams = recyclerView.getLayoutParams as the stack trace suggests, I cannot call setMargin anymore as that method does not exist for ViewGroup.LayoutParams.
任何帮助将不胜感激.
尝试一下.您可以参考此以获取更多信息.
Try this out. You can refer to this for more info.
ViewGroup.MarginLayoutParams marginLayoutParams = new ViewGroup.MarginLayoutParams(mRecyclerView.getLayoutParams());
marginLayoutParams.setMargins(0, 10, 0, 10);
mRecyclerView.setLayoutParams(marginLayoutParams);