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):

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));

Finally, 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);

This should work everywhere that RecyclerView does (API 7+). If you're using the pre-release version of RecyclerView, you may encounter this error:

Error:Execution failed for task ':sample:processDebugManifest'.

Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version L declared in library com.android.support:recyclerview-v7:21.0.0-rc1

You can work around this by adding <uses-sdk tools:node="replace" />. [See the sample app's manifest for an example.] (https://github.com/timehop/sticky-headers-recyclerview/blob/master/sample/src/main/AndroidManifest.xml#L3-L5)

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

• I haven't tested this with ItemAnimators yet.

0.2 (10/3/2014) - Add StickyRecyclerHeadersTouchListener

0.1 (10/2/2014) - Initial Release