Who doesn’t know java’s exception java.lang.UnsupportedClassVersionError?
Java throws the exception when class is compiled to a newest version of Virtual Machine that is trying to run. For instance, run a class compiled to J2SE 5 in a JRE 1.4
There’s many ways to find the version from a .class file. One of then need a hexadecimal editor to verify the Magic Numbers. An another way, the easier way, you’ll just need run the command javap.
javap are located in $JAVA_HOME/bin (same path of javac and java).
javap -v <class_file_path>/Test.class
You will able to check the version in “major version” line.
Classfile /C:/Users/USER/Test.class Last modified 26/08/2014; size 532 bytes MD5 checksum cb9054fefbbaa410d3asd38fb82c7c54afb Compiled from "Test.java" public class Test SourceFile: "Test.java" minor version: 0 major version: 51 ...
With this result we discovered that class was compiled to version 51 (JRE 7).
You can find respective JRE version in table above:
|Number version||JRE version|
Don’t forget about to comment if it helped!