Changing of Java

When changing Java versions, you may have some problems.

Just delete the former .class files, and the former .jar files created with the previous version of Java, before re-creating them.

Typically, when compiling a .java file, you will end up with an error like this:

$ javac -Xlint MyTestClass.java
MyTestClass.java:28: error while writing MyTestClass: MyTestClass.class (Operation not supported)
class MyTestClass{
       ^
1 error
 

The re-creation won't work: the formerly created files must be deleted.