What version of javac built my jar?

Question

How can I tell what version of the Java compiler was used to build a jar? I have a jar file, and it could have been built in any one of three JDKs. We need to know exactly

Answer 1

The Java compiler (javac) does not build jars, it translates Java files into class files. The Jar tool (jar) creates the actual jars. If no custom manifest was specified, the default manifest will specify which version of the JDK was used to create the jar.