Compressed bitmaps in Java

A bitmap is an efficient array of boolean values. They are commonly used in bitmap indexes. The Java language has a bitmap class: BitSet.

Unfortunately, the Java BitSet class will not scale to large sparse bitmaps—the Sun implementation does not use compression.

I published a new free alternative: JavaEWAH.



  • Glen Newton gave me the idea for this project.
Tweet about this on Twitter0Share on Facebook0Share on Google+0Share on Reddit0Email this to someone

5 thoughts on “Compressed bitmaps in Java”

  1. I have just downloaded the software. I have just one preliminary question: how are you sure that EWAH is not patented. In other words why do you think that a patent on WAH does not cover EWAH as well.

  2. Hi,

    Great paper, great wok, nothing to add… I’m currently in Dublin, Ireland, it is amazing that I can download your paper and enjoy your work. Thanks a lot!

  3. Daniel,

    Is there a way to check whether a bit at the given position is set? In the constant time of course, not using the iterator. Thanks in advance.

Leave a Reply

Your email address will not be published. Required fields are marked *