[SOLVED] How can I pass a list as a command-line argument with argparse in Java

How can I pass a list as a command-line argument with argparse in Java

Using the Java port of the Argparse4j library, how can I pass a list as a cli argument? I know there are answers to this querstion in Python, but am looking for a Java example.

For example how can I access the --list argument in this code as an actual Java List type.

ArgumentParser parser = ArgumentParsers.newFor("main").build();
parser.addArgument("-l", "--list")
    .help("Argument list to parse");

Then run the code with

java Main --list foo bar fizz

Solution

To parse the list of arguments you are just missing a parameter when constructing your ArgumentParser, from your code:

// note that "main" should be your class name not your main method IIRC
ArgumentParser parser = ArgumentParsers.newFor("main").build();

parser.addArgument("-l", "--list")
      .nargs("*") // Here is the trick, this will accept 0 or N arguments
      .help("Argument list to parse");

And same as in your Python answer link nargs will also accept + which means it requires at least one argument.

To parse/get the list of arguments you would need:

//I'm assuming you have a main method with args parameter here
Namespace ns = parser.parseArgs(args);
List<String> list = ns.getList("list");

System.out.println("Parsed list: " + list);

For this call java main --list arg1 arg2 arg3 it will output:

Parsed list: [arg1, arg2, arg3]