Java – how to check the jdk version used to compile a .class file

java

Possible Duplicate:
Tool to read and display Java .class versions

I'm trying to debug a

"Bad version number in .class file'

error in java, is there a way for me to check which version the .class files are?

I'm using JRE1.5.0_6, but my JDK is version 1.6.0_13.

I'm compiling with compatibility mode set to 1.5 in eclipse which I thought would work…

Best Solution

You're looking for this on the command line (for a class called MyClass):

On Unix/Linux:

javap -verbose MyClass | grep "major"

On Windows:

javap -verbose MyClass | findstr "major"

You want the major version from the results. Here are some example values:

  • Java 1.2 uses major version 46
  • Java 1.3 uses major version 47
  • Java 1.4 uses major version 48
  • Java 5 uses major version 49
  • Java 6 uses major version 50
  • Java 7 uses major version 51
  • Java 8 uses major version 52
  • Java 9 uses major version 53
  • Java 10 uses major version 54
  • Java 11 uses major version 55