Passing a .JAR program (ran from terminal) a text file as input

Question

I have created a java program that other testers will use to help with their testing. I will be sending them a zip file with the .jar, a readme.txt, and main.properties.txt file.

The main.properties.txt file is a template for the testers to input their DB access credentials. They will update the main.properties file with their db cred's and then attempt to run the .jar from the terminal or command line. The issue I am running into is this. My program needs this updated main.properties.txt file so it can create the connections to our DB's.

What instructions do I need to give in my readme so my program can successfully find the main.properties.txt? Does the main.properties need to be in the same directory as the .jar? Can the testers just create a file on their desktop or documents folders to put the .jar and main.props?

The other question I have is how do I pass this file to my program once its ran from the terminal? Currently it is really easy, because the main.props is part of my program and I can just do something like

Properties prop = new Properties();
FileInputStream in = new FileInputStream("src/main/resources/main.properties");
prop.load(in);
in.close();

But now main.properties is not part of the project anymore. I don't know how to change the code above so that it can find the text from a directory on the local. The location in which they wish to put their main.properties is out of my control so writing a static path will not work. Please help!

Answer 1

There are many ways, I'll show you two.

You need a File object that points to the main.properties file. Then you create a stream on this object new FileInputStream(File) , as you already did by using a String.

The problem of course is to get a relative path to main.properties.txt which works on all systems, regardless where the jar-File is located.

1. Desktop

In this case the main.properties.txt is located at the users desktop. Here is how you access it:

File desktop = new File(System.getProperty("user.home"), "Desktop");
File target = new File(desktop, "main.properties.txt");

Alernativly, if you plan to distribute configuration and property files that do not require user interaction, you may want to use locations like Temp or Documents (Windows).

2. Relative to the jar

Probably one of your best options. Assume the target is in the same folder than the jar-File (or at least in a fix structure relative to the jar). Here is how you access it (related question: how-to-get-the-path-of-a-running-jar-file):

CodeSource codeSource = YourMainClass.class.getProtectionDomain().getCodeSource();
File jarFile = new File(codeSource.getLocation().toURI().getPath());
File jarDir = jarFile.getParentFile();

File target = new File(jarDir, "main.properties.txt");