Command Line Flags in Minitab

Here’s the translated code and explanation in Java, formatted for Hugo:

Our first program will demonstrate how to use command-line flags in Java. We’ll use the Apache Commons CLI library, which provides similar functionality to Go’s flag package.

import org.apache.commons.cli.*;

public class CommandLineFlags {
    public static void main(String[] args) {
        // Define the options
        Options options = new Options();
        options.addOption("word", true, "a string");
        options.addOption("numb", true, "an int");
        options.addOption("fork", false, "a bool");
        options.addOption("svar", true, "a string var");

        // Create a parser
        CommandLineParser parser = new DefaultParser();
        HelpFormatter formatter = new HelpFormatter();

        try {
            // Parse the command line arguments
            CommandLine cmd = parser.parse(options, args);

            // Retrieve the values
            String word = cmd.getOptionValue("word", "foo");
            int numb = Integer.parseInt(cmd.getOptionValue("numb", "42"));
            boolean fork = cmd.hasOption("fork");
            String svar = cmd.getOptionValue("svar", "bar");

            // Print the values
            System.out.println("word: " + word);
            System.out.println("numb: " + numb);
            System.out.println("fork: " + fork);
            System.out.println("svar: " + svar);
            System.out.println("tail: " + String.join(" ", cmd.getArgs()));

        } catch (ParseException e) {
            System.out.println(e.getMessage());
            formatter.printHelp("CommandLineFlags", options);
            System.exit(1);
        }
    }
}

To experiment with the command-line flags program, first compile it and then run the resulting class file directly.

$ javac -cp commons-cli-1.4.jar CommandLineFlags.java

Try out the compiled program by first giving it values for all flags.

$ java -cp .:commons-cli-1.4.jar CommandLineFlags -word opt -numb 7 -fork -svar flag
word: opt
numb: 7
fork: true
svar: flag
tail:

Note that if you omit flags they automatically take their default values.

$ java -cp .:commons-cli-1.4.jar CommandLineFlags -word opt
word: opt
numb: 42
fork: false
svar: bar
tail:

Trailing positional arguments can be provided after any flags.

$ java -cp .:commons-cli-1.4.jar CommandLineFlags -word opt a1 a2 a3
word: opt
...
tail: a1 a2 a3

The Apache Commons CLI library allows flags to appear anywhere in the command line, unlike Go’s flag package which requires all flags to appear before positional arguments.

Use -h or --help flags to get automatically generated help text for the command-line program.

$ java -cp .:commons-cli-1.4.jar CommandLineFlags -h
usage: CommandLineFlags
 -fork           a bool
 -numb <arg>     an int
 -svar <arg>     a string var
 -word <arg>     a string

If you provide a flag that wasn’t specified, the program will print an error message and show the help text again.

$ java -cp .:commons-cli-1.4.jar CommandLineFlags -wat
Unrecognized option: -wat
usage: CommandLineFlags
...

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Command Line Flags in Minitab