Commons CLI API - Option Class

Q

How to use org.apache.commons.cli.Option class to define options?

✍: FYIcenter.com

A

Commons CLI API allows you to define and add options directly to the org.apache.commons.cli.Options object.

It also allows you to define options using the org.apache.commons.cli.Option class and add them to the org.apache.commons.cli.Options object later.

Here is good Java example of using org.apache.commons.cli.Option class to define options with Commons CLI API, ShortOptionTest.java:

// Copyright (c) 2018 FYIcenter.com
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.HelpFormatter;
import org.apache.commons.cli.UnrecognizedOptionException;

public class OptionClassTest {
   public static void main(String[] args) throws Exception {
      Options options = new Options();
       
      // Define a short option: -h
      Option help = new Option("h", "Print this help message");
      options.addOption(help);
      
      // Define a long option: --version -version -v
      Option version = new Option("v", "version", false, "Print version info");
      options.addOption(version);
      
      // Define a short option with argument: -n 3
      Option n = new Option("n", true, "Number of output lines");
      options.addOption(n);

      // Define a long option with argument: --input ..., -input ..., -i ...
      Option input = new Option("i", "input", true, "Input string");
      options.addOption(input);

      try {
         // Parse options
         CommandLineParser parser = new DefaultParser();
         CommandLine cmd = parser.parse(options, args);
         
         int lines = 1; 
         if (cmd.hasOption("n")) {
            lines = Integer.parseInt(cmd.getOptionValue("n"));
         }
         
         if (cmd.hasOption("h")) {
            help(options);
         } else if (cmd.hasOption("version")) {
            System.out.println("OptionClassTest version 1.0.0");
         } else if (cmd.hasOption("input")) {
            for (int i=0; i<lines; i++) {
               System.out.println("Hello "+cmd.getOptionValue("input"));
            }
         }
      } catch (UnrecognizedOptionException e) {
         System.out.println("Invalid options: "+e.getOption());
         help(options);
      }
   }

   public static void help(Options options) {
      // Print options
      HelpFormatter formatter = new HelpFormatter();
      formatter.printHelp("OptionClassTest", options);
   }
}

You can compile and run it with commons-cli-1.4.jar:

C:\fyicenter>javac -cp C:\fyicenter\commons-cli-1.4\commons-cli-1.4.jar OptionClassTest.java

C:\fyicenter>java -cp .;C:\fyicenter\commons-cli-1.4\commons-cli-1.4.jar OptionClassTest -h
usage: OptionClassTest
 -h                 Print this help message
 -i,--input <arg>   Input string
 -n <arg>           Number of output lines
 -v,--version       Print version info

C:\fyicenter>java -cp .;C:\fyicenter\commons-cli-1.4\commons-cli-1.4.jar OptionClassTest --version
OptionClassTest version 1.0.0

C:\fyicenter>java -cp .;C:\fyicenter\commons-cli-1.4\commons-cli-1.4.jar OptionClassTest -i world
Hello world

C:\fyicenter>java -cp .;C:\fyicenter\commons-cli-1.4\commons-cli-1.4.jar OptionClassTest -i world -n 3
Hello world
Hello world
Hello world

 

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2020-05-15, 481👍, 0💬