How do I parse command line arguments in Java?

Question

What is a good way of parsing command line arguments in Java?

Answer 1

Check these out:

• http://commons.apache.org/cli/
• http://www.martiansoftware.com/jsap/

Or roll your own:

• http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html

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For instance, this is how you use commons-cli to parse 2 string arguments:

import org.apache.commons.cli.*;  public class Main {       public static void main(String[] args) throws Exception {          Options options = new Options();          Option input = new Option("i", "input", true, "input file path");         input.setRequired(true);         options.addOption(input);          Option output = new Option("o", "output", true, "output file");         output.setRequired(true);         options.addOption(output);          CommandLineParser parser = new DefaultParser();         HelpFormatter formatter = new HelpFormatter();         CommandLine cmd = null;//not a good practice, it serves it purpose           try {             cmd = parser.parse(options, args);         } catch (ParseException e) {             System.out.println(e.getMessage());             formatter.printHelp("utility-name", options);              System.exit(1);         }          String inputFilePath = cmd.getOptionValue("input");         String outputFilePath = cmd.getOptionValue("output");          System.out.println(inputFilePath);         System.out.println(outputFilePath);      }  } 

usage from command line:

$> java -jar target/my-utility.jar -i asd                                                                                        Missing required option: o  usage: utility-name  -i,--input <arg>    input file path  -o,--output <arg>   output file 

Answer 2

Take a look at the more recent JCommander.

I created it. I’m happy to receive questions or feature requests.