jvm-bytecode

Tool to read and display Java .class versions

Do any of you know of a tool that will search for .class files and then display their compiled versions?

I know you can look at them individually in a hex editor but I have a lot of class files to look over (something in my giant application is compiling to Java6 for some reason).

Solution

  • Use the javap tool that comes with the JDK. The -verbose option will print the version number of the class file.

    > javap -verbose MyClass
Compiled from "MyClass.java"
public class MyClass
  SourceFile: "MyClass.java"
  minor version: 0
  major version: 46
...

    To only show the version:

    WINDOWS> javap -verbose MyClass | find "version"
LINUX  > javap -verbose MyClass | grep version