Say you have a
config.properties file containing various configuration details. This file is placed under the resources folder and loaded using classpath. Then you can override the file during runtime by specifying a different file to the classpath command line argument. Let's say that the main class is
Main.java inside
com.example.test package and the
test.jar is our program. Use the following command to override the
config.properties file.
java -classpath .;test.jar;config.properties; com.example.test.Main