System.getProperty returns null for defined property

Question

I have a property TOOLS_DIR that i exported in bash

I have the following line in my java file:

String toolsDir = System.getProperty("TOOLS_DIR");

Why is this returning null? is the a compatibility issue with linux or something?

Answer 1

Environment variables and properties aren't the same thing. If you want to pass in an environment variable as property you have to add the following to your java invocation:

-DTOOLS_DIR=$TOOLS_DIR

Alternatively, you can use System.getEnv()

Answer 2

Java system properties have nothing to do with shell environment variables.

You can assign a java system property when you invoke the virtual machine, for example:

java -DTOOLS_DIR=/somewhere org.example.MyClass

Answer 3

Try this instead:

String toolsDir = System.getenv("TOOLS_DIR");

The getProperty(...) method returns java vm properties (like user.dir, java.version). The getenv(...) method is for environment variables.