[git] Git: copy all files in a directory from another branch

How do I copy all files in a directory from another branch? I can list all of the files in that directory by doing

git ls-tree master:dirname

I can then copy all of the files individually by doing

git checkout master -- dirname/filename

However, using wildcards has so far been a total fail. This does nothing:

git checkout master -- dirname/*.png

Though I guess I can use a bash script to do that, there has to be an easier way, right?

If there are no spaces in paths, and you are interested, like I was, in files of specific extension only, you can use

git checkout otherBranch -- $(git ls-tree --name-only -r otherBranch | egrep '*.java')