If you are doing #Java #programming, and you've downloaded a jar of #Javadoc documentation for some library, #Firefox can directly display it without unpacking the jar!
Just prepend `jar:file://`, and append `!/index.html`, to form a URL.
For example, if the jar is located at:
/home/you/.m2/repository/com/example/example-library/1.0/example-library-1.0-javadoc.jar
Then use this URL:
jar:file:///home/you/.m2/repository/com/example/example-library/1.0/example-library-1.0-javadoc.jar!/index.html