Android percent screen width in RecyclerView item

Question

How would I get a RecyclerView's item height to be, say, 30% of the screen's height?

I can't simply use a ConstraintLayout or a PercentFrameLayout/PercentRelativeLayout, since those position child layouts relative to parent layouts, whose size might not match the screens.

Preferably, I'd like to do this in pure XML (and not have to use any Runnables to get the screen height dynamically).

EDIT

To clarify, since a lot of solutions suggest restraining the height of the RecyclerView, that's not the intent. The RecyclerView should still populate the screen. Here's what I'm talking about, using the screen width (instead of height):

The idea is to get the card's width to be 33% the screen's width, while keeping the RecyclerView's width unaltered as it scrolls past the screen horizontally.

question from:https://stackoverflow.com/questions/51201482/android-percent-screen-width-in-recyclerview-item

Answer 1

You can override one of the LayoutManager methods used by your RecyclerView to force specific size:

recyclerView.setLayoutManager(new LinearLayoutManager(this){
    @Override
    public boolean checkLayoutParams(RecyclerView.LayoutParams lp) {
        // force height of viewHolder here, this will override layout_height from xml
        lp.height = getHeight() / 3;
        return true;
    }
});

This is assuming your RecyclerView fits the screen.

If you want more complex solution (custom layout manager with per-item control & percent inflation straight from from XML) see this answer.