xargs jar tvf - does not work

Objective: to list files in all jars.

This works:

for f in `find . -name "*.jar"`; do jar tvf $f; done

This works too:

find . -name "*.jar" -exec jar tvf {} \;

This does not (it does not print any output):

find . -name "*.jar" | xargs jar tvf

Why does the latter not work?