Picocli: arbitrary length of paired parameters

Question

In Picocli, is it possible to pair parameters of an arbitrary length? For example:

grades Abby 4.0 Billy 3.5 Caily 3.5 Danny 4.0

where each pair must have a name and a grade but the total length is unknown, i.e.:

grades <name> <grade> [<name> <grade>]*

A parameter map is the closest that appears might work, e.g.

@Parameters(index = "0..*") Map<String, float> grades;

would parse:

grades Abby=4.0 Billy=3.5 Caily=3.5 Danny=4.0

into the map but it'd be nicer if the equals wasn't there...

Answer 1

Update: picocli 4.3 has been released with improved support for positional parameters in argument groups.

@Command(name = "grades", mixinStandardHelpOptions = true, version = "grades 1.0")
public class Grades implements Runnable {

    static class StudentGrade {
        @Parameters(index = "0") String name;
        @Parameters(index = "1") BigDecimal grade;
    }

    @ArgGroup(exclusive = false, multiplicity = "1..*")
    List<StudentGrade> gradeList;

    @Override
    public void run() {
        gradeList.forEach(e -> System.out.println(e.name + ": " + e.grade));
    }

    public static void main(String[] args) {
        System.exit(new CommandLine(new Grades()).execute(args));
    }
}

Running the above program with this input:

Alice 3.5 Betty 4.0 "X Æ A-12" 3.5 Zaphod 3.4

Produces the following output:

Alice: 3.5
Betty: 4.0
X Æ A-12: 3.5
Zaphod: 3.4

---

Prior to picocli 4.3, applications can do the following to accomplish this:

import picocli.CommandLine;
import picocli.CommandLine.Command;
import picocli.CommandLine.Parameters;

import java.math.BigDecimal;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

@Command(name = "grades", mixinStandardHelpOptions = true, version = "grades 1.0")
public class Grades implements Runnable {

    @Parameters(arity = "2",
            description = "Each pair must have a name and a grade.",
            paramLabel = "(NAME GRADE)...", hideParamSyntax = true)
    List<String> gradeList;

    @Override
    public void run() {
        System.out.println(gradeList);
        Map<String, BigDecimal> map = new LinkedHashMap<>();
        for (int i = 0; i < gradeList.size(); i += 2) {
            map.put(gradeList.get(i), new BigDecimal(gradeList.get(i + 1)));
        }
    }

    public static void main(String[] args) {
        int exitCode = new CommandLine(new Grades()).execute(args);
        System.exit(exitCode);
    }
}