Welcome to CodeRanch Anna.
I'm not too sure if I would go right to Java 9 as it just came out within that last week.
Most/much of Java is setup to be backwards compatible, however I'm sure that there are some breaking changes between versions.
How you manage the upgrade does depends somewhat on your environment and other system dependencies. For instance if you are running WebSphere with a specific version of Java then you may need to upgrade WebSphere first.
Even thought Java does try to be backwards compatible, the code that you are responsible for could be using third party libraries (pdf library,
word library etc) which may break with newer versions of Java.
I do not think that there is a quick and easy process here, regardless of which
IDE you are using.
Here are the broad steps:
A) Get a listing of system dependencies which are used in your environment that may need the code your are working with. For example if WebSphere is part of the equation then see if there is a reason that they are using the version Java that they are currently using. If they need to use a specific version of Java for whatever reason then maybe your job is done. Or maybe you have to do some extra
testing with a newer version of the dependancy to see what happens with a newer version of Java.
B) Get a listing of libraries that the code is using to see how they would react to an upgrade of Java. Maybe these libraries cannot function in newer Java versions and your job is done. Or maybe you have a find alternatives.
Once you are 100% sure that you have both steps A and B from the above listing covered then I would suggest making a test environment with Java 8 to see what happens when compiled with Java 8.
- If this works then you would need to migrate that to the production systems/environment.
- If this does not work then try with Java 7. If it works with Java 7 then I would migrate the Java 7 to the reset of the production systems/environment.
- If it works with Java 7 but not Java 8 then you have to become a detective and find out why.
This whole process could be done within a week if everything goes smoothly and you have a small production systems/environment. However more then likely this process will take more then a week.
Hope this helps out,
Pete