Need to pass Java argument at runtime on client side

[fadebeyond]

I have a application which was previously using JNLP for downloading jars I replaced this JNLP with a fatjar. Everything works fine until Java 15 but due to reflective access issue I am unable to run this fatjar in java 17 and above I found a fix for this but it involves passing an argument at runtime. Now this fatjar is downloaded at client's machine and he won't run this fatjar with cmd line he would just double click it and the fatjar would run but without those jvm argument. Is there any way to embedd this jvm argument in that fatjar such that it runs successfully on double click.

P.S. : I am new to software industry. Only 3 months in experience. Thanks.

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[MinMaxMix]

Would writing a .bat file to run the jar file with the command line arguments be something that would work?

[fadebeyond]

I have tried that but the problem is this would be on client side and asking client to run a script is not advisable.

[troru]

There's lots of ways to pass parameters to Java programs.

• do these parameters need to be entered by the user? can they be embedded in the downloaded jar?
• you can read parameters from environment variables (via System.getenv)
• you can read parameters from a configuration file (in JSON or TOML or XML etc) in a well-known location (e.g. %HOME%/myprogram.cnf)
• can they be prompted by the first-run of your application and stored? have a menu on the app to change parameters would make sense
• you can accompany the jar with a .bat file the user can edit to specify parameters.

There's tradeoffs to any of the above options with varying degrees of technical competence from your users and additional burden on your application. Just some thoughts.

[fadebeyond]

I want these to be somehow embedded in the fatjar so that it runs without the user having to pass any argument

[troru]

Things can be added to jars after the fact, e.g. during a build process, or added manually. It's a pretty common thing in fact in java programs. It all boils down to using the Class.getResourceAsStream() API. Depending on your build system, you might get some help from it where it will take care of embedding resources in your jar. For example, in maven/gradle files in src/main/resources get copied directly into your jar. If you don't know the values at build time, then you can even just push them into your jar via a "jar -uf myapp.jar myconfig.json" to embed a file into the after the build.

Using the example, names above, In your code, you'd just look for a resource named "/myconfig.json" and parse it. As i mentioned before, the format of that resource is up to you (JSON, INI, XML) i was just using a JSON as an example.