HelloWorld.java

Welcome to the Nanowar Of Steel's first GitHub project, and first ever example of a source-code song. The aim of this project is to support and enforce "True metal programming", that basically means: "write code so badly that only you can sing it".

You can find the source-code video in the link below: https://www.youtube.com/watch?v=yup8gIXxWDU

Here is the Nanowar Of Steel official website.

Here is the Nanowar Of Steel Youtube Channel.

Some important notes:

1. Beware of Joey De Caio, if set to null It may suddenly cancel the program execution with a NullPointerException.
2. metal variable is very important! If it is set to "false", it may trigger the Joey De Caio variable mentioned above.
3. tizio and foo are very close friends.
4. pippo isn't tizio's friend, but he's been flirting with foo.
5. In the comments "manage" should be renamed as "handle" (we all wish "manage" was the right word, but it's not).
6. The constructor argument is used to control the number of executions. However, It may be completely useless if the execution is canceled by Joey De Caio.
7. "Write once, run anywhere" means lityerally anywhere (e.g. Hellfest).
8. songRefrain() identifies itself as a void method.

Below you will find a super detailed guide to the program, of course written with ChatGPT.

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HelloWorldMainLauncherClass

This project contains a simple Java application that demonstrates the basic usage of loops, conditionals, and handling null-pointer exceptions. The main functionality includes printing "Hello World!" multiple times based on a user-defined parameter and intentionally introducing a bug to highlight error handling.

Overview

The HelloWorldMainLauncherClass performs the following tasks:

1. Initialization: Accepts an integer parameter (foo) that controls how many times "Hello World!" will be printed.
2. Song Refrain: Prints "Hello World!" twice—first using a for loop and then using a while loop.
3. Exception Handling: Contains a method falseMethod() that introduces a NullPointerException by calling length() on a null string to simulate error handling.

Features

• Hello World printing: Outputs the message "Hello World!" a number of times based on the provided parameter.
• Loops: Demonstrates basic usage of for and while loops in Java.
• Exception simulation: Introduces a NullPointerException for demonstration purposes.
• Basic Java structure: Showcases constructor usage, instance variables, and method definitions.

Prerequisites

• Java Development Kit (JDK) 8 or higher.
• A Java IDE (like IntelliJ IDEA, Eclipse, or NetBeans) or a command-line environment to compile and run the Java program.

Installation

To set up and run this project locally, follow these steps:

1. Clone the repository:

   git clone https://github.com/NanowarOfSteel/HelloWorld.git

2. Navigate into the project directory:

   cd HelloWorld

3. Compile the Java file:

   javac HelloWorldMainLauncherClass.java

4. Run the program:

   java HelloWorldMainLauncherClass

Usage

Once you run the program, you will see the following output:

Hello World Programmer Start
Hello World!
Hello World!
Hello World!
Hello World!
Program Finished!
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.length()" because "joeyDeCaio" is null
    at HelloWorldMainLauncherClass.falseMethod(HelloWorldMainLauncherClass.java:35)
    at HelloWorldMainLauncherClass.main(HelloWorldMainLauncherClass.java:27)

Configuration

The number of times "Hello World!" is printed can be controlled by changing the parameter passed to the constructor of HelloWorldMainLauncherClass. For example:

HelloWorldMainLauncherClass tizio = new HelloWorldMainLauncherClass(3);

This will print "Hello World!" three times.

Code Explanation

1. Constructor: The constructor takes an integer foo that determines how many times the message will be printed.

   public HelloWorldMainLauncherClass(int foo) {
       super();
       this.foo = foo;
   }

2. songRefrain() Method: The method contains two loops—for and while—both of which print "Hello World!" the number of times specified by foo.

   public void songRefrain() {
       for (int i = 0; i < foo; i++) {
           System.out.println("Hello World!");
       }
   
       int pippo = 0;
       while (pippo < foo) {
           System.out.println("Hello World!");
           pippo++;
       }
   }

3. falseMethod() Method: This method deliberately introduces a bug by attempting to call length() on a null string.

   public void falseMethod() {
       boolean metal = false;
       if (metal == false) {
           String joeyDeCaio = null;
           joeyDeCaio.length();
       }
   }

Notes:

• Bug introduction: The purpose of falseMethod() is to demonstrate a scenario where an exception is thrown. The NullPointerException is handled by the JVM, but no explicit exception handling is implemented in this case.

• Extending the Program: You can extend the program by adding more features like exception handling, more complex message outputs, or additional loops and conditionals.

Docker Guide

This repository contains a Dockerfile that automates the process of building and running a Java application using Maven. The Docker image is built in two stages: the first stage builds the application with Maven, and the second stage runs the application with a minimal OpenJDK 17 image.

Table of Contents

• Prerequisites
• Build and Run Instructions
• Usage
• Cleaning Up
• Notes

Prerequisites

Before building and running the Docker image, make sure you have the following installed:

• Docker: Install Docker
• Maven: (Optional) Maven is only needed locally for building the project if you're not using the Docker build.

Build and Run Instructions

1. Clone the repository

First, clone the repository containing the project and the Dockerfile to your local machine:

git clone <your-repository-url>
cd <your-repository-directory>

2. Build the Docker image

You can build the Docker image using the following command. Make sure you're in the root directory of the project, where the Dockerfile is located:

docker build -t my-java-app .

This command will:

1. Use an official Maven image to build the application.
2. Package the application into a JAR file.
3. Use a slim OpenJDK 17 image to run the resulting application.

3. Run the Docker container

After the build is complete, you can run the Docker container using:

docker run -p 8080:8080 my-java-app

This will start the application and expose it on port 8080. You can adjust the port if necessary.

Usage

Once the container is running, the application should be available at http://localhost:8080. This assumes your application is set to listen on port 8080. You can modify the port mapping as needed.

If the application requires specific environment variables or configuration, you can pass them at runtime like so:

docker run -p 8080:8080 -e ENV_VAR_NAME=value my-java-app

Cleaning Up

To stop the running container, you can use:

docker ps  # Find the container ID
docker stop <container_id>

You can also remove the container and image once you're done:

docker rm <container_id>  # Remove the container
docker rmi my-java-app    # Remove the image

Notes

• Multi-stage build: The Dockerfile uses a multi-stage build to ensure the final image is small and optimized for running the application. The first stage uses the Maven image to build the application, and the second stage uses a slim JDK image to run it.
• JAR file location: The final JAR file is copied from the /target directory in the Maven build stage to the working directory in the runtime stage (/app).

Troubleshooting

• Issue: The application isn't starting or doesn't work as expected.

  • Solution: Check the logs for any error messages by running:

    docker logs <container_id>

• Issue: Docker build fails due to missing dependencies.

  • Solution: Make sure all necessary dependencies are listed in your pom.xml file, and try running mvn clean install locally to check for issues before attempting the Docker build.

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License

This project is licensed under the IronAvantgarde Publishing & Napalm Records License - see the Napalm Records Website for more details.

Contributing

Feel free to fork this repository, submit issues, or open pull requests if you'd like to improve this code. Contributions are always welcome!

Contacts

Do you want some buggy, personalized and singable code by Nanowar Of Steel? Please contact us here.