CommandPrompt

📄 This README is also available in Turkish

🙏 Acknowledgement

This project was inspired by an example application presented by Oğuz Karan during a Java programming course as part of the topic on reflection.
While the implementation and enhancements were done by me, the core idea and architectural approach are based on the structure introduced by my instructor.

---

A lightweight and extensible Java framework for building command-line interfaces using annotations.
Easily bind methods to commands and run them interactively from a customizable prompt.

✨ Features

• Annotation-based command registration (@Command, @Commands)
• Support for multiple aliases per command
• Helpful error messages for unknown commands or argument mismatches
• Builder-based configuration (prompt text, suffix, error messages)
• Uses Java Reflection to collect and invoke command methods at runtime

---

🚀 Getting Started

1. Create your command class

If you annotate a method with @Command and leave the value element empty, the command name will default to the method name. Write the operations as void methods and annotate them with @Command. If a method is annotated with multiple @Commands, each name can be used to trigger the method.

import commandprompt.annotation.Command;
import commandprompt.annotation.Commands;

public class MyCommands {

    @Commands({@Command("hello"), @Command("hi")})
    private void greet() {
        System.out.println("Hello!");
    }

    @Command("echo")
    private void echo(String message) {
        System.out.println(message);
    }

    @Command("help")
    private void help() {
        System.out.println("Try: hello, echo, help");
    }
}

2. Register it and run the prompt

Create your CommandPrompt instance as shown below, and pass an instance of the class where you defined your commands to the register method.

import commandprompt.CommandPrompt;

public class Main {
    public static void main(String[] args) {
        CommandPrompt prompt = new CommandPrompt.Builder()
            .setPrompt("cli")
            .setSuffix(">")
            .register(new MyCommands())
            .build();

        prompt.run();
    }
}

⚙️ Customization

You can configure the prompt using the builder:

Method	Purpose
setPrompt(String prompt)	Sets prompt prefix
setSuffix(String suffix)	Sets prompt suffix
setWrongNumberOfArgumentsMessage(...)	Error message for wrong args
setInvalidCommandMessage(...)	Error message for bad command
setParameterStringTypeErrorMessage(...)	Message for type mismatch

🛠 Under the Hood

This project uses Java Reflection API to:

• Scan registered objects for methods annotated with @Command.
• Extract command names and parameter information.
• Dynamically invoke methods when a matching command is entered.