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jbock is a command line parser, similar to JCommander and picocli. It is an annotation processor that generates custom parsing code at compile time. jbock requires Java 11.

Basic example

A command line interface is defined as an abstract class which has a @Command annotation. In this class, each abstract method defines a named option or a positional parameter. As an annotation processor, jbock has access to the method's return type before erasure. It uses this full type information to determine multiplicity.

@Command(name = "rm", description = "Coffee time!")
abstract class DeleteCommand {

  /* Path, not Optional<Path>:
   * This positional parameter is required (multiplicity = 1).
   */
  @Parameter(index = 0,
             description = "A positional parameter.")
  abstract Path path();

  /* OptionalInt, not int or Integer:
   * This named option is optional (multiplicity = 0..1).
   */
  @Option(names = {"-v", "--verbosity"},
          description = "A named option.")
  abstract OptionalInt verbosity();
}

See here for the code this generates: DeleteCommandParser.java

The generated parser is usually used in a main method:

public static void main(String[] args) {
    DeleteCommand command = new DeleteCommandParser().parseOrExit(args);
    // ...
}

In addition to parseOrExit, there is also a highly configurable parse method with no side effects. Please see the wiki for details.

Sample projects

• jbock-maven-example
• jbock-gradle-example