populate GridLayoutManager first by row and then by column

Question

I'm having an issue while populating a recycler view with a GridLayoutManager.

I need to fulfill the first row, and after this is complete, go to the second row. I did an algorithm that reorders the list so it's being shown properly and I can get the item clicked without doing any mapping-unmapping thing. This is working fine, but the trouble appears when all the items can be shown on the screen without scrolling.

For example, I have 4 items and I need to show them in a 2-row grid layout (horizontal layout). The screen has space for 3 items, so I need them to be in the first row, while the 4th item should be the only one in the second row.

To give you a picture of what I have by default:

0 2
1 3 

And what I need is:

0 1 2
3

Any ideas?

Edit: As requested, here is the code I'm using:

    GridLayoutManager layoutManager = new GridLayoutManager(getContext(),2,LinearLayoutManager.HORIZONTAL, false);

Boraginaceous

did you find a sloution – Electromotive

Answer 1

When you are defining your gridLayoutManager, you specify the number of columns

RecyclerView rView = new RecyclerView(this);
rView.setLayoutManager(new GridLayoutManager(context, <your number of columns>));

Setting this value to 3 (in your case) would result in three columns, with two rows. Your array adapter populates the fields from left to right, then top to bottom.

Buckskins

Failing this, you could add "null" or " " to your array until it is evenly divisible by the number of columns you want (in this instance, a total of 6 elements). This would populate two additional columns in the second row with nothing, but still adding them to the layout. – Buckskins

The first approach was the one I tried and didn't work. By default, it's not displaying the items as you mentioned (check at the question how it was ordering the items). The second approach shouldn't work! I ended reordering the whole list to match the expected result, but without a clear solution to solve this. Thanks anyway! – Boraginaceous

How are you declaring your gridLayoutManager, can you update your answer with some of your existing code? – Buckskins

Updated. Remember that I want an horizontal grid! – Boraginaceous

Answer 2

Not sure if this will solve your issue but you can have dynamic columns based on items type or position (or similar logic)

val layoutManager = GridLayoutManager(requireContext(), columnsCount)
layoutManager.spanSizeLookup = object: GridLayoutManager.SpanSizeLookup() {
    override fun getSpanSize(position: Int): Int {
        return adapter.getColumnsCount(position)
    }
}
rvList.layoutManager = layoutManager

and in your adapter a method that returns the columns

fun getColumnsCount(position: Int): Int {
    return when (getItem(position).type) {
        ItemType.FIRST -> 1
        ItemType.SECOND -> 3
    }
}

====== If all you need is to fit the items on screen, you can have fixed width items and calculate how many fit the screen:

val columnCount = recyclerView.width / resources.getDimensionPixelSize(R.dimen.grid_item_width)

Leela