How to pass arguments from command line to gradle

project.group is a predefined property. With -P, you can only set project properties that are not predefined. Alternatively, you can set Java system properties (-D).

As of Gradle 4.9 Application plugin understands --args option, so passing the arguments is as simple as:

build.gradle

plugins {
    id 'application'
}

mainClassName = "my.App"

src/main/java/my/App.java

public class App {
    public static void main(String[] args) {
        System.out.println(args);
    }
}

bash

./gradlew run --args='This string will be passed into my.App#main arguments'

or in Windows, use double quotes:

gradlew run --args="This string will be passed into my.App#main arguments"

My program with two arguments, args[0] and args[1]:

public static void main(String[] args) throws Exception {
    System.out.println(args);
    String host = args[0];
    System.out.println(host);
    int port = Integer.parseInt(args[1]);

my build.gradle

run {
    if ( project.hasProperty("appArgsWhatEverIWant") ) {
        args Eval.me(appArgsWhatEverIWant)
    }
}

my terminal prompt:

gradle run  -PappArgsWhatEverIWant="['localhost','8080']"

As noted in a comment, my solution is superceded by the newer built-in --args option in gradle. See this answer from @madhead or this similar question.

---

Building on Peter N's answer, this is an example of how to add (optional) user-specified arguments to pass to Java main for a JavaExec task (since you can't set the 'args' property manually for the reason he cites.)

Add this to the task:

task(runProgram, type: JavaExec) {

  [...]

  if (project.hasProperty('myargs')) {
      args(myargs.split(','))
  }

... and run at the command line like this

% ./gradlew runProgram '-Pmyargs=-x,7,--no-kidding,/Users/rogers/tests/file.txt'