sticky-headers-recyclerview

This decorator allows you to easily create section headers for RecyclerViews using a LinearLayoutManager in either vertical or horizontal orientation.

Credit to Emil Sjölander for creating StickyListHeaders, a library that many of us relied on for sticky headers in our listviews.

Here is a quick video of it in action (click to see the full video):

Download

compile 'com.timehop.stickyheadersrecyclerview:library:0.4.0@aar'

Usage

There are three main classes, StickyRecyclerHeadersAdapter, StickyRecyclerHeadersDecoration, and StickyRecyclerHeadersTouchListener.

StickyRecyclerHeadersAdapter has a very similar interface to the RecyclerView.Adapter, and it is recommended that you make your RecyclerView.Adapter implement StickyRecyclerHeadersAdapter.

There interface looks like this:

public interface StickyRecyclerHeadersAdapter<VH extends RecyclerView.ViewHolder> {
  public long getHeaderId(int position);

  public VH onCreateHeaderViewHolder(ViewGroup parent);

  public void onBindHeaderViewHolder(VH holder, int position);

  public int getItemCount();
}

The second class, StickyRecyclerHeadersDecoration, is where most of the magic happens, and does not require any configuration on your end. Here's an example from onCreate() in an activity:

mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
mAdapter = new MyStickyRecyclerHeadersAdapter();
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setLayoutManager(new LinearLayoutManager(context));
mRecyclerView.addItemDecoration(new StickyRecyclerHeadersDecoration(mAdapter));

StickyRecyclerHeadersTouchListener allows you to listen for clicks on header views. Simply create an instance of StickyRecyclerHeadersTouchListener, set the OnHeaderClickListener, and add the StickyRecyclerHeadersTouchListener as a touch listener to your RecyclerView.

StickyRecyclerHeadersTouchListener touchListener =
    new StickyRecyclerHeadersTouchListener(recyclerView, headersDecor);
touchListener.setOnHeaderClickListener(
    new StickyRecyclerHeadersTouchListener.OnHeaderClickListener() {
      @Override
      public void onHeaderClick(View header, int position, long headerId) {
        Toast.makeText(MainActivity.this, "Header position: " + position + ", id: " + headerId,
            Toast.LENGTH_SHORT).show();
      }
    });
mRecyclerView.addOnItemTouchListener(touchListener);

The StickyHeaders aren't aware of your adapter so if you must notify them when your data set changes.

    mAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
      @Override public void onChanged() {
        headersDecor.invalidateHeaders();
      }
    });

Item animators don't play nicely with RecyclerView decorations, so your mileage with that may vary.

Compatibility

This should work in API 14+.

Known Issues

• The header views aren't recycled at this time. Contributions are most welcome.

• I haven't tested this with ItemAnimators yet.

Version History

0.4.0 (4/16/2015) - Code reorganization by danoz73, fixes for different sized headers, performance improvements

0.3.6 (1/30/2015) - Prevent header clicks from passing on the touch event

0.3.5 (12/12/2014) - Add StickyRecyclerHeadersDecoration.invalidateHeaders() method

0.3.4 (12/3/2014) - Fix issues with rendering of header views with header ID = 0

0.3.3 (11/13/2014) - Fixes for padding, support views without headers

0.3.2 (11/1/2014) - Bug fixes for list items with margins and deleting items

0.2 (10/3/2014) - Add StickyRecyclerHeadersTouchListener

0.1 (10/2/2014) - Initial Release