Is there anything like VirtualEnv for Java?

Asked 4/9, 2011 at 15:15 Answered 3/12, 2018 at 15:23

Solved java python virtualenv jvm-languages

Is there anything similar to Python virtualenv for Java or JVM Languages?

Highly answered 4/9, 2011 at 15:15 Comment(1)

Why are you asking this? (is there some other deeper problem?) – Beitch 31/5, 2022 at 11:14

From what I understand, virtualenv enables you to have separate library installation paths, effectively separate "virtual" Python installations.

Java doesn't have the concept of a "system-wide installed" library^(*): It always searches the classpath for the libraries to be loaded. Since the classpath can be (and needs to be!) defined for each application, each application can pick-and-choose which libraries and which versions it wants to load.

If you go down one level deeper and have a single application that somehow needs two different versions of the same library at the same time, then you can do even that with some classpath trickery. It can get complicated, but it's definitely possible (OSGi is one example where this is supported, even Tomcat with two separate webapplications does this).

I've seens some references to security in the virtualenv description: Java has a pretty thorough security system built in. In server applications it's often turned off because it's just easier to configure this way, but you can easily configure what exactly a Java application is allowed to do.

^{(*) Almost, there are extensions or extension libraries, but they aren't used a lot and even those can easily be loaded from arbitrary directories.}

Divulge answered 4/9, 2011 at 15:23 Comment(4)

This may be true for packages, but another thing python virtual environments help manage is versions of python itself. How do Java devs handle working on projects that use different versions of Java? – Colleague 19/2, 2020 at 2:40

Script starting Java application that needs a specific installation of Java virtual machine, usually sets path to it in the JAVA_HOME variable. – Lucilla 30/12, 2021 at 13:40

The Java install also depends on some system libraries. – Beitch 31/5, 2022 at 11:12

Problem arises when some 3rd party inject its java version into path, so your java gets the wrong version. maven,gradle handles artifacts, and can force java version, but it just stops if the first java it finds has wrong version. currently the best solution seems to be using containers. – Ranita 10/8, 2022 at 8:9

Build tools like Ant, Maven, and gradle are the the closest thing to pip or easy_install.

The concept of virtualenv is done by the classpath. So there is no real need of virtualenv for Java

Groundspeed answered 8/8, 2012 at 6:0 Comment(0)

Yes(see http://www.jenv.be/), like many other languages (Ruby, Python, Go, R, Php, etc. etc.).

Knockabout answered 3/12, 2018 at 15:23 Comment(1)

The intent & behaviour of this tool seems to be more closely aligned with Python’s tox. A virtual environment can only be associated with a single Python version, and it can be challenging to have multiple Python versions installed on a system simulataneously. Tox takes care of this problem, similarly to how jenv seems to be taking care of that problem for Java. – Repudiation 25/5 at 12:6

I know this may be a little late , but Groovy/Java has gvm http://gvmtool.net/ which is the Groovy version of Ruby's renv.

I would respectfully agree with Gautam K, luthur. Dependency and package version management for projects is not the same as an isolated self-contained virtual environment to maintain different project.

My 2 cents -W

Mcgowan answered 7/2, 2013 at 0:29 Comment(0)

I have also been looking for a similar solution to simplify switching context between projects that use different Maven versions/settings and/or Java SDKs without having to modify M2_HOME and JAVA_HOME settings every time.

To this end, I developed a solution that helps execute mvn commands with the appropriate configuration based on per-project settings (stored in a .mvn folder).

See: https://github.com/AlejandroRivera/maven-env

Be aware that this only helps if you're using Maven to build and/or run your project.

Cytolysis answered 21/12, 2014 at 18:49 Comment(1)

Why not to use Maven profiles ? – Dyarchy 25/1, 2021 at 13:27

I'm confused by the assertion that "Java doesn't have the concept of a 'system-wide installed' library". What would you call the jar files in $JAVA_HOME/jre/lib and $JAVA_HOME/jre/lib/ext?

Regardless of whether or not Java "needs" a tool like virtualenv, it seems that something that allowed you to quickly switch between different Java environments (e.g. Java 6 with such-and-such security extensions, Java 7, etc.) would be handy - even if all it was actually doing under the covers was manipulating the PATH, JAVA_HOME, and CLASSPATH env variables.

Agenda answered 11/7, 2014 at 15:48 Comment(1)

I think this should have been a comment on my answer. I didn't see it before, so sorry for my late response: The jre/lib/ext holds extension libraries, which I've mentioned briefly in the footnote and they are indeed not used a lot. Yes, I agree there is some utility in quickly switching between JREs/JDKs and some such tools exist (for example Debian/Ubuntu has the alternatives system which allows you to switch the JDK used for the different java commands (among many other things)). – Divulge 4/9, 2014 at 12:27

Maven, you can explicitly specify which packages you would use in a java project

Azerbaijan answered 30/7, 2012 at 1:52 Comment(4)

Maven is a build tool and has nothing in common with virtualenv ! Which is a totally different concept . – Highly 30/7, 2012 at 5:25

!!!!!!!!maven config file can specify which version and packages you would use in a specific java project, isn't it!!!!!!!!!!!!!!!! – Azerbaijan 15/8, 2012 at 15:15

OP's question is a classic XY problem. He is asking how to map a Python solution to Java instead of asking how to solve a problem. The question should be "How do I manage dependencies in Java?" and the correct answer is to use Maven or one of it's competitors. – Usanis 25/11, 2012 at 21:23

@Usanis you can't know what problem he is trying to solve (as he does not ask this). He could be 'just curious' as well – Beitch 31/5, 2022 at 11:13

Java as a language does not need the sandboxing features of virtualenv but a JVM Language like Jython can have VirtualEnv to use different environments without any conflict.

It is outlined in this blog post

Quote:

Get virtualenv installed for Jython. Just type "jeasy_install virtualenv". Once that finishes you should have a 'virtualenv' tool in the Jython installation's bin folder.

So when using Jython different frameworks and packages can be used without any conflict with global packages.

Highly answered 11/9, 2011 at 1:26 Comment(0)

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