Parse CLI command lines

CLI Parser

CLI Parser is a tiny (10k jar), super easy to use library for parsing various kinds of command line arguments or property lists. Using annotations on your fields or JavaBean properties you can specify what configuration is available. Here is an example:

public class Loader {

  private static Boolean hdfs = false;

  @Argument(alias = "r", description = "Regular expression to parse lines", required = true)
  private static String regex;

  @Argument(alias = "k", description = "Key column", required = true)
  private static String key;

  @Argument(alias = "p", description = "Key prefix")
  private static String prefix;

  @Argument(alias = "c", description = "Column groups", delimiter = ",")
  private static String[] columns;

  @Argument(alias = "n", description = "Column names", delimiter = ",")
  private static String[] names;

  @Argument(alias = "h", description = "Redis host")
  private static String host = "localhost";

  @Argument(alias = "p", description = "Redis port")
  private static Integer port = 6379;

  public static void main(String[] args) throws IOException {
    // unparsed will contain all unparsed arguments to the command line
    List<String> unparsed = Args.parseOrExit(Loader.class, args);
    // Loader's fields will be populated after this line or the program will exit with usage

In this case we are configuring static fields, but you can also use the same system with instances. If you pass in a wrong command line argument you will get the usage message:

Usage: com.sampullara.cli.Example
  -hdfs [flag]
  -regex (-r) [String] Regular expression to parse lines
  -key (-k) [String] Key column
  -prefix (-p) [String] Key prefix
  -columns (-c) [String[,]] Column groups
  -names (-n) [String[,]] Column names
  -host (-h) [String] Redis host (localhost)
  -port (-p) [Integer] Redis port (6379)

That message will print out the names and aliases of the arguments, type, description and a default value for the parameter if there is one. You can add it to your code with:


Here is the license:

Copyright 2012 Sam Pullara

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   See the License for the specific language governing permissions and
   limitations under the License.