如何以编程方式设置recyclerview的高度？

我试过了,

recyclerview.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,100));

但它不起作用.

尝试设置这样的高度,

ViewGroup.LayoutParams params=recyclerview.getLayoutParams();
params.height=100;
recyclerview.setLayoutParams(params);