How to pass enviornment variables to jar file?

Question

I want to set run configuration option : Environment variable while running JAR and run it using java code. How to set environment option while running jar through java code?

Answer 1

ENV_VAR=some-value java -jar path/to/theJar.jar

You can then access that in Java via System.getEnv('ENV_VAR')

In java you can also do system properties

java -Dsome.system.prop=some-value -jar path/to/theJar.jar

you can then access the system props in code via System.getProperty('some.system.prop')

Answer 2

You simply need to pass your new variables to the exec method of Runtime, check this: https://stackoverflow.com/a/8607281/5032541

This is from the oracle doc : https://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html#exec(java.lang.String,%20java.lang.String[])

To get the runtime, simply do Runtime.getRuntime()

There is an example:

List<String> env = new LinkedList<>();
System.getenv().forEach((key, value) -> env.add(key+"="+value));
env.add("MY_SUPER_NEW_ENV_VAR=AND_MY_SUPER_VALUE");
Runtime runtime = Runtime.getRuntime();
runtime.exec("/bin/bash", env.toArray(new String[0]));