Command Line Flags in Logo

Here’s the translation of the Go code to Java, formatted in Markdown suitable for Hugo:

import java.util.Arrays;

public class CommandLineFlags {
    public static void main(String[] args) {
        // We'll use the Apache Commons CLI library for command-line parsing in Java
        // This is a simplified version using basic Java functionality

        String word = "foo";
        int numb = 42;
        boolean fork = false;
        String svar = "bar";

        for (int i = 0; i < args.length; i++) {
            String arg = args[i];
            if (arg.startsWith("--word=")) {
                word = arg.substring(7);
            } else if (arg.startsWith("--numb=")) {
                numb = Integer.parseInt(arg.substring(7));
            } else if (arg.equals("--fork")) {
                fork = true;
            } else if (arg.startsWith("--svar=")) {
                svar = arg.substring(7);
            }
        }

        System.out.println("word: " + word);
        System.out.println("numb: " + numb);
        System.out.println("fork: " + fork);
        System.out.println("svar: " + svar);
        System.out.println("tail: " + Arrays.toString(Arrays.copyOfRange(args, 4, args.length)));
    }
}

Command-line flags are a common way to specify options for command-line programs. For example, in wc -l the -l is a command-line flag.

Java doesn’t have a built-in package for parsing command-line flags like Go’s flag package. However, there are third-party libraries like Apache Commons CLI that provide similar functionality. For simplicity, this example uses a basic approach to parse command-line arguments.

In this example, we declare variables for each flag with default values. We then iterate through the command-line arguments to parse and set these values.

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

$ javac CommandLineFlags.java

Try out the compiled program by providing values for all flags:

$ java 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 CommandLineFlags --word=opt
word: opt
numb: 42
fork: false
svar: bar
tail: []

Trailing positional arguments can be provided after any flags:

$ java CommandLineFlags --word=opt a1 a2 a3
word: opt
...
tail: [a1, a2, a3]

This basic implementation doesn’t provide automatic help text generation or error handling for unrecognized flags. In a real-world scenario, you would typically use a library like Apache Commons CLI, which provides more robust command-line parsing capabilities, including automatic help text generation and error handling.