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 cancelled by Joey De Caio. 7. "Write once, run anywhere" means literally 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) 21 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:

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

1. Navigate into the project sources directory:

bash cd HelloWorld

1. Compile and run the Java file:

bash java src/main/java/it/nanowar/ofsteel/helloworld/HelloWorldMainLauncherClass.java

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!" six times.

Code Explanation

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

JBang Guide

This repository contains a jbang catalog that allows you to run the HelloWorld program with the command jbang hello@nanowarofsteel/hello.

Table of Contents

• Prerequisites
• Usage

JBang Prerequisites

To use the jbang catalog, you need to have jbang installed. You can install jbang here.

JBang Usage

To run the HelloWorld program with jbang, you can use the following command directly without cloning the repository:

jbang hello@nanowarofsteel/HelloWorld

If you have cloned the repository, you can run the program with the following command:

jbang hello

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
• Performance considerations

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

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, then point out the location of the Dockerfile with the -f option:

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 21 image to run the resulting application (kinda).

Usage

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

docker run --rm my-java-app

Cleaning Up

If you didn't use the option --rm when instanciating the container, you will have to manually 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).

Performance considerations

In order to achieve better performance experience this code live. Due to resource allocation issues there are only limited possibilities:

• FRIDAY 21 FEBRUARY 2025: Vienna, Austria - Simm City

• SATURDAY 22 FEBRUARY 2025: Leipzig, Germany - Hellraiser

• SUNDAY 23 FEBRUARY 2025: Stuttgart, Germany - Halle, Im Wizemann

• MONDAY 24 FEBRUARY 2025: Hamburg, Germany - Kaiserkeller (Grosse Freiheit)

• WEDNESDAY 26 FEBRUARY 2025: Paris, France - La Machine du Moulin Rouge

• THURSDAY 27 FEBRUARY 2025: Pratteln, Switzerland - Z7 Konzertfabrik

• FRIDAY 28 FEBRUARY 2025: Villeurbanne, France - La Rayonne

• SATURDAY 1 MARCH 2025: Lindau, Germany - Club Vaudeville

• SUNDAY 2 MARCH 2025: Nuremberg, Germany - HIRSCH

• TUESDAY 4 MARCH 2025: Aarhus, Denmark - VoxHall

• WEDNESDAY 5 MARCH 2025: Tilburg, Netherlands - 013

• THURSDAY 6 MARCH 2025: Frankfurt, Germany - Zoom Frankfurt

• FRIDAY 7 MARCH 2025: Wrocław, Poland - Transformator

• SATURDAY 8 MARCH 2025: Budapest, Hungary - Barba Negra

• SUNDAY 9 MARCH 2025: Krakow, Poland - Kwadrat

• MONDAY 10 MARCH 2025: Berlin, Germany - Columbia Theater

• WEDNESDAY 12 MARCH 2025: Antwerp, Belgium - Kavka Zappa

• THURSDAY 13 MARCH 2025: Bochum, Germany - Matrix

• FRIDAY 14 MARCH 2025: Drachten, Netherlands - Poppodium Iduna

• SATURDAY 15 MARCH 2025: Strasbourg, France - Le Molodoï

• SUNDAY 16 MARCH 2025: Munich, Germany - Backstage

• FRIDAY 4 - SATURDAY 5 APRIL 2025: epic fest denmark 2025: - Roskilde-Hallerne, Roskilde, Denmark

Further information about upcoming resources can be found here: https://tour.nanowar.it

Troubleshooting

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

• Solution: Check the logs for any error messages by running: bash 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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Docker compose guide

Prerequisites

• Docker: Install Docker
• Docker compose: Install Docker Compose

Build and Run Instructions

1. Clone the repository

Do as described in Docker Build and Run Instructions

2. Build and Run

With Docker Compose building and running are done with one command (run in the project root):

docker compose up

This command will build and run the project serving it on port 8080.

For further explanations see the comments in file: docker-compose.yaml

By running docker compose up the output will be captured by the execution.

You can pass the execution context to the docker daemon by running

docker compose up -d

Cleaning Up

If you ran docker compose without the -d flag stop the execution by pressing ctrl+c

If you ran docker compose -d you can stop the execution by running

docker compose down

within the directory where the file docker-compose.yaml is located

Run

docker compose rm

to remove the stopped container.

Then do as described in Cleaning Up for Docker except for the removal of the stopped container part

Troubleshooting (only for Mac or Linux)

If you get this error: Error response from daemon: driver failed programming external connectivity on endpoint helloworld-app-1 (1769c92017f2d2da48adc989bd2321855e3152f6a11932c18ed36e7df443f0ae): failed to bind port 0.0.0.0:8080/tcp: Error starting userland proxy: listen tcp4 0.0.0.0:8080: bind: address already in use'

It means the port 8080 is already binded (maybe by the previous docker execution without cleaning up).

To solve it find the process running on port 8080 by running

lsof -i tcp:8080

Note the PID value of the output and kill the process by running

kill <PID>

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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.