What java version is needed for JUnit 4.8

Question

I am trying to run JUnit test with a 1.5 JRE, but get the error Message:

java.lang.UnsupportedClassVersionError: Bad version number in .class file

When I switch to JRE 1.6 (actually a JDK but that shouldn't matter, right?) everythings works fine.

So the questions are:

• Do we really need Java 6 for the current JUnit version?
• what is the newest JUnit version, that works with Java 5?

Answer 1

The current .jar file for JUnit 4.8.2 was compiled with/for Java 5 (class version number is 49.0).

I remember an earlier version accidentally being built with Java 6 (and without the -target switch), but that was simply a mistake.

Answer 2

The pom.xml of Junit says jdk 1.5. http://github.com/KentBeck/junit/blob/master/pom.xml

Answer 3

A spot check of a few classes shows that the JUnit 4.8.2 jar file was compiled with java 5, or with the java 6 compiler with the -target option set so that it makes java5-compatible class files.

A far more likelier explanation is that you've accidentally compiled the test you wanted to run with a Java 6 JDK. What does:

javap -verbose -classpath YOUR_TOP_DIRECTORY com.yourname.YourTest

say at the top of its output for "major version"? If it says 50, then the problem is that you've compiled your test class for java 6 only. You need to either use a JDK 5 compiler or pass the option -target 1.5 to your compiler.