Android: custom separator (or even item) in ListView depening on content of item

I've a ListView with items containing information about places with a rating and the distance to the current location.

The items are sorted into groups:

• Group 1: within 500m
• Group 2: 500m - 1km
• Group 3: 1km - 1.5km
• ...

Withing these groups the items are sorted by their rating.

Now I put out these items via my custom adapter (extension of BaseAdapter) into the ListView, which works perfectly.

However, what I'd like to do is to put a separator before the each first item of each group. This separator can be a TextView saying e.g. 500m - 1km followed by all the ListView items in that group.

Any idea on how to realize this?