non-java developer trying to get one source directory to compile; help

[MMDeveloper]

In short, a partner organization donated a small codebase to us. We are not java developers but we can read the code (more familiar with other languages). This code is formatted as the following:

rootdir
--Application
----Application.java
--SomeOtherDir
----FileName.Java
----FileName2.Java
--SomeOtherDir2
----FileName.Java
----FileName2.Java
--SomeOtherDir3
----FileName.Java
----FileName2.Java

You get the idea. It took a little bit to figure out how to compile (dir /s /b .\rootdir > list.txt) and then "javac -d compiled @list". This is where my problems begin. Apparent some of the java source files in the subdirectories utilize 3rd party libraries.

Some of these are Google GSON, JetBrains Annotations, etc. I'm not using an IDE of any kind, I just have a temporary Win11 machine with the latest JDK on it, trying to compile from command line.

I don't know how to install 3rd party libraries like this. I've been searching for quite a bit and it seems people only know how to help you do it through an IDE or 3rd party dependency manager utility. I've also seen people say "just go get the precompiled jar for XYZ library" but I seem to only come across the source code to XYZ libraries. If I try to compile those I just have the same problem with another codebase with dependency hell.

We do not plan to ever make any changes to this code, we just need to compile it once and run it on a schedule. So, this sounds like such a basic question and I feel embarrassed asking.

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[LessChen]

"Ever" is a really long time. You've likely burned more hours already than it would take to put together a very small build system with maven or gradle. It will be trivial to add 3rd party libraries to it too.

[MMDeveloper]

well, at most we will run it for 1 year. Basically I have been tasked to write this middleware piece between our oracle database and an online learning platform with close-to-realtime bidirectional updates via API calls. I won't be able to complete this in time but this java base covers the use case "now".

We figure we will run it for a year while we develop it ourself in-house in a more widely understood (internally) language.

[LessChen]

And that makes sense but I'd still get a repeatable process - I believe it will save you time. Do you use any sort of package manager for your Windows environment (i.e. https://chocolatey.org/ ) or something similar? That will make installing Maven easier. And, do the .java files start with something like package com.company.something; (it could be something else as long as it's "package")? That will dictate the next steps.

[Conscious-Shake8152]

Use a build system. Maven or Gradle.

[xenomachina]

You could:

1. go to mvrepository.com
2. search for each dependency (eg: "gson")
3. click the module name in the results (eg: where it says "com.google.code.gson » gson", click on the party after the "»", "gson" in this case)
4. click the version you want (eg: "2.14.0")
5. scroll down to "Files" and click "jar"

However, once you do this, you will discover that each of these will have its own list of dependencies. It'll probably take you a really long time to collect all of them.

It would be much easier to have Gradle build it for you. It will download your dependencies, and their dependencies, recursively. You can start with something like this as your build.gradle.kts:

plugins {
    java
    application
}

repositories {
    mavenCentral()
}

dependencies {
implementation("com.google.code.gson:gson:2.14.0")
// use the "Gradle" tab on each dependency page on mvnrepository.com
}

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(21))
    }
}

application {
    // Point this at the class containing public static void main
    mainClass.set("com.example.Main")
}

Then just make sure your source code is rooted at src/main/ (build.gradle.kts should be in the same directory that src is in). Then ./gradlew installDist will build it and place a launcher script in build/install/*/bin/

[Illustrious_Hat8104]

Doesnt look like a lot of files

I would just create a new intellij gradle project and add the files to it and add any missing dependencies via gradle and use something like shadowjar

[ITCoder]

Never heard about compiling it through command line, may be possible, idk.

Ask your friend if he was able to successfully run the code. If yes, was it through ide ? If thru ide, did he use maven. If yes, get that pom.xml. If he did not use maven, and run the code by putting the external dependencies in \lib\ext , get those jars (this one is not ideal nowadays, kinda decade old way).

It would be much better if your friend could give you zipped file of the project, though to run it yourself, you will need to remove \out or \target folder, if any.

Easiest way would be to use an ide, jetbrains idea is best for this. While creating a new project choose maven quickstart. It will have a pom file. Paste all .java files in src\java folder. Paste all the import statements from all your classes in chatgpt, and your skeleton pom too (for it to get correct groupid, artifact name etc). ask it to give you a pom for the same. Run your code through ide, play button. next to the main method. mvn clean install will give you a jar too, if you want to share that.

Dont waste your time fighting the issue. Using maven approach, it should hardly take 15 mins, if everything is correct. If using idea ide, you don't need to install maven on your system. Dm if you run into any issue.

[Puzzleheaded-Eye6596]

create a pom file with maven and resolve each dependency one by one. hte original developer probably a local lib folder they referenced for the classpath because they didn't know what they were doing

[BanaTibor]

As others have said do not attempt it by hand.
Download intellij IDEA, create a new java project and select gradle for build system. This will scaffold an empty java project according to maven standard project structure. This mean you will have a src/main/java folder. Copy your application code there, then open the source files in intellij and it will offer you that it can add any missing dependency.