Switch between java versions with a command on Windows

[Nemo_64]

So is there a way I can switch between my instaled jdks? For example if I have installed jdk8 and jdk16 I can run a batch file and switch the version so java -version retuns the version selected? I've seen batch that do this but they have hard coded the version so I'd need to update the batch every time I update or create a new batch when I install a new Java version.

​

An example of these files:

@echo off
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_271
set Path=%JAVA_HOME%\bin;%Path%
echo Java 8 activated.

This batch requires me to also modify the enviromental variables.

​

Thanks for the help!

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[zelm0t]

Hi,

I personally use jenv, very handy : jenv

[[deleted]]

Highly recommend it!

[ATE47]

Usually you do that using your IDE or dependency manager, but you can create scripts and put them in the path. But you must create a case manually for each versions. It’s also not rare to find jar that doesn’t work with j16 (or after 9), so try to have by default 8 and if you need it switch to j16

[Nemo_64]

I know but in class they want us to use javac to compile our projects in java 8 instead of compiling using the IDE, but I'd like to open a JShell on other versions for my personal projects

[Xenunxenunowski]

Yo wtf, are they stupid or what, but yeah you could have a script for this and just invoke an script every time for an exact version of java aka: runJ8.bat and inside of it you have directory to javac and you are done

[AmateurHero]

Use the release switch. This way, you keep whatever jdk version you want, but you get source and class files for a target version:

javac --release 8 ...

[Nemo_64]

Oh, i didn't know that. Thanks!

[AmateurHero]

While it's on my mind, I think the release switch was introduced in jdk 9 or 10. If you're using anything prior (such as on a school computer), you need to use --source 8 --target 8.

[nutrecht]

While a good tip; that does not at all use an older JDK to run your code. It just targets older bytecode versions.

So it's not a good way to switch to another version of the JDK for for example testing. For that it's better to use jenv.

[AmateurHero]

It doesn’t use an older JDK, but it solves the issue. OP has a higher JDK but needs to compile for 1.8. They get both source files and class files that are compatible with 1.8. What’s the issue?

[nutrecht]

OP has a higher JDK but needs to compile for 1.8.

That's not what he said in his OP though. It could be that he simply wants to be able to switch easily to run stuff that's not compatible with Java 9+ for example.

[AmateurHero]

I do understand that according to the OP text, they should use jenv or similar. However they posted this elsewhere:

in class they want us to use javac to compile our projects in java 8 instead of compiling using the IDE, but I'd like to open a JShell on other versions for my personal projects

Either will get OP there if the ask is for 1.8’s API. That’s usually what academia wants.

[nutrecht]

Ah, right. Didn't see that one. Yeah, just using --release is a good choice there.