Force RecyclerView to bottom of page in layout

android, android-layout, java, xml

Solution

Many thanks to everyone who contributed, but I have found a programmatic solution outside of the `layout` files. In case anyone else is looking for a solution to this problem, I found one here.

It appears as if there is an issue with `RecyclerView` currently where it doesn't wrap content. The answer is to construct a custom class that extends `LinearLayoutManager`. I have posted the solution that worked for me below - most of it is copy and pasted from the answer given in the link I quoted. The only small issue is that it doesn't account for the extra space added by decorations, which is why I had to make a small tweak to the following line near the end of the code:

//I added the =2 at the end.    
measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin + 2;

Here is the code in its entirety:

public class HomeLinearLayoutManager extends LinearLayoutManager{

    HomeLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    private int[] mMeasuredDimension = new int[2];

    @Override
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                          int widthSpec, int heightSpec) {
        final int widthMode = View.MeasureSpec.getMode(widthSpec);
        final int heightMode = View.MeasureSpec.getMode(heightSpec);
        final int widthSize = View.MeasureSpec.getSize(widthSpec);
        final int heightSize = View.MeasureSpec.getSize(heightSpec);
        int width = 0;
        int height = 0;
        for (int i = 0; i < getItemCount(); i++) {
            measureScrapChild(recycler, i,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    mMeasuredDimension);

            if (getOrientation() == HORIZONTAL) {
                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
                }
            } else {
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
                }
            }
        }
        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        setMeasuredDimension(width, height);
    }

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        View view = recycler.getViewForPosition(position);
        if (view != null) {
            RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
            int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight(), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom(), p.height);
            view.measure(childWidthSpec, childHeightSpec);
            measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
            measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin + 2;
            recycler.recycleView(view);
        }
    }
}

Thanks again.

Problem

I have a page that consists of an `ImageView`, and a `RecyclerView`. The `RecyclerView` contains a small number of items (currently three) and only takes up around a quarter of the screen on my test device. However, despite trying numerous layout options, I cannot get the `RecyclerView` to effectively wrap its content and take up just enough space required to contain these three rows, and leave the rest of the space for my `ImageView`. To help illustrate what I mean, I have drawn two diagrams. The first shows what I would like to happen, and the second what is happening: So far, I have tried several different combinations of `RelativeLayout` - for instance, I will set `RecyclerView` to `layout:align_ParentBottom` and the second `RelativeLayout` that contains the `ImageView` to `layout:alignComponent` so that its bottom matches the `RecyclerView` top (this would normally drag the `ImageView` layout so that it fills any reminaing space, which is what I would like to happen.) The `RecyclerView` though just keeps occupying all the space it can, even though it only contains a few rows. The current "solution" I have is to place everything inside a `LinearLayout` and set less `gravity` to the `RecyclerView`, but it isn't ideal, because on different emulators it wont line up completely with the bottom of the screen, and in others there isn't enough room and the `RecyclerView` becomes scrollable. Thanks in advance for any help and suggestions anyone can offer.

Original source

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