Package picocli

Annotation Type CommandLine.Mixin

  • @Retention(RUNTIME)
@Target({FIELD,PARAMETER})
public static @interface CommandLine.Mixin

    Fields annotated with @Mixin are "expanded" into the current command: @Option and @Parameters in the mixin class are added to the options and positional parameters of this command. A CommandLine.DuplicateOptionAnnotationsException is thrown if any of the options in the mixin has the same name as an option in this command.

    The Mixin annotation provides a way to reuse common options and parameters without subclassing. For example: 

     @Command(name="HelloWorld")
 class HelloWorld implements Runnable {

     // adds the --help and --version options to this command
     @Mixin
     private HelpOptions options = new HelpOptions();

     @Option(names = {"-u", "--userName"}, required = true, description = "The user name")
     String userName;

     public void run() { System.out.println("Hello, " + userName); }
 }

 // Common reusable help options.
 class HelpOptions {

     @Option(names = { "-h", "--help"}, usageHelp = true, description = "Display this help and exit")
     private boolean help;

     @Option(names = { "-V", "--version"}, versionHelp = true, description = "Display version info and exit")
     private boolean versionHelp;
 }
    Since:
    3.0

    • Optional Element Summary

      Optional Elements 
      Modifier and Type Optional Element Description
      String name
      Optionally specify a name that the mixin object can be retrieved with from the CommandSpec.

    • Element Detail

      • name

        String name
        Optionally specify a name that the mixin object can be retrieved with from the CommandSpec. If not specified the name of the annotated field is used.
        Returns:
        a String to register the mixin object with, or an empty String if the name of the annotated field should be used
        Default:
        ""