eclipse - No source attachment in Java -

i trying use external .jar file in project. have put .jar file in project's /lib folder, , have referenced in build path. however, when try use in code, can't javadoc it, nor can see actual code referenced classes. says has no source attachment. meant source attachment? have javadoc folder came it, when attach build path, still reports not found javadoc classes. ideas on that?

i want able see javadoc.

the .jar file generated packed classes of java code. jars come java doc , code , others won't.

for recent eclipse versions:

right-click jar in question (in referenced jars, not physical jar) , choose preferences -> javadoc. here give correct location (zip/url) correct javadoc. (select validate!)

for older eclipse versions:

first: navigate jar in eclipse project explorer (to left) , try open aclass of jar. then, see warning it has no source attachment, , button attach source code.

then, push button, select "external folder" , navigate folder source have.