Java 10, already!

Java 9 we hardly knew ye, yet here we are and today was the GA release of Java 10. This is especially true for those of us using Spring boot as we just got official Java 9 support a couple of weeks ago and now 10 is out. From my standpoint the big features of the release are the Root Certificates. Java 9 shipped without root certificates if you used OpenJDK which in my mind makes it less useable as now you have to with that, you can’t just run it and go. That is what was keeping me on Oracle’s releases of Java. Now in Java 10 there is no difference with the oracle JDK and the OpenJDK so I will probably just deploy my apps on OpenJDK in the future. That simplifies Linux installation as now you can just run apt-get install and go. Before I used to have to add the ppa for Oracles and install it and then deal with the strong crypto policy files. All those old pain points are gone.

The next big change is Parallel Full GC support in G1GC. In Java 9 they changed the default VM to G1 and now they have enhanced it so that if you have to run a full collection it will at least run in parallel and reduce the pause time for your application.

The feature all the developers are talking about is local variable type inference. So now you can write:

var list = new ArrayList<String>();

Instead of:

List<String> list = new ArrayList<>();

The thinking being the name of the variable is the most important part and this may make the code more readable. For me I am not completely sold on this change. I think in some circumstances it may make the code more readable, but in other cases it will be worse, so I am taking a wait and see approach with using this style.

The other small developer feature that looks good to me, are APIs to create unmodifiable collections. I could see myself using that a lot, and it will be nice to no longer need Guava for some of these things. Instead of thehorrible old:

List<String> list = new ArrayList<>();
list.add("String 1");
list.add("String 2");

return Collections.unmodifiableList(list);

And making sure that you aren’t leaking the original reference you can just do:

var list = List.of("String1", "String2");

or if you have the list shown in the first example and you want to lock it down you can use:

return List.copyOf(list);

which I think reads better than:


and it is obvious that it is making a copy so you don’t have to worry about leaking the original reference.

Other than that there is better support for the VM to realize it is running in a docker container and only assume the resources assigned to the container instead of reading the OS values. Otherwise there isn’t a lot there. That being said if you have managed to get on Java 9 already in production you need to upgrade right away as 9 is no longer supported, and you need 10 to make sure that you have all the latest security fixes.

Finally I will leave you with this:

Java version text

The times they are a changing…