S01L02 – HelloWorld Java program without Maven

Title:
Getting Started with Java: Building Your First “Hello World” Application in IntelliJ IDEA

Table of Contents

  1. Introduction
  2. Setting Up Your Development Environment
    1. Installing IntelliJ IDEA
    2. Configuring the JDK
  3. Creating a New Java Project
    1. Initializing the Project
    2. Understanding the Project Structure
  4. Writing Your First Java Program
    1. Adding Sample Code
    2. Running the Application
  5. Packaging Your Application into a JAR File
    1. Creating an Artifact
    2. Configuring the Manifest
    3. Building the JAR File
  6. Troubleshooting Common Issues
  7. Conclusion

Introduction

Welcome to your journey into Java programming! This eBook is designed to guide beginners and developers with basic knowledge through the process of creating a simple “Hello World” application using IntelliJ IDEA without the complexities of Maven. Whether you’re setting up your first development environment or looking to understand the fundamentals of Java project structure, this guide has you covered.

Importance and Purpose

Starting with a “Hello World” program is a traditional first step in learning any programming language. It allows you to:

  • Understand Development Tools: Familiarize yourself with IntelliJ IDEA, one of the most popular Integrated Development Environments (IDEs) for Java.
  • Set Up Your Environment: Configure the Java Development Kit (JDK) essential for compiling and running Java applications.
  • Learn Project Structure: Gain insights into how Java projects are organized, including source files and output directories.
  • Build Confidence: Successfully running your first program builds the foundation for more complex projects.

Pros and Cons

Pros Cons
Quick setup with IntelliJ IDEA Requires installation of IntelliJ and JDK
Clear understanding of project structure Manual configuration without Maven can be tedious
Immediate feedback with console output Limited scalability for larger projects

When and Where to Use

This guide is perfect for:

  • Beginners: Individuals new to Java programming.
  • Developers Seeking Simplicity: Those who prefer starting without the additional layers that build tools like Maven introduce.
  • Educational Purposes: Instructors and learners aiming to grasp the basics of Java and IDE usage.

Setting Up Your Development Environment

Before diving into coding, it’s essential to set up your development environment correctly. This section will walk you through installing IntelliJ IDEA and configuring the Java Development Kit (JDK).

Installing IntelliJ IDEA

IntelliJ IDEA is a powerful IDE for Java development. Follow these steps to install it:

  1. Download IntelliJ IDEA:
    • Visit the JetBrains website and choose the appropriate version for your operating system.
  2. Run the Installer:
    • Follow the on-screen instructions to install the IDE.
  3. Launch IntelliJ IDEA:
    • After installation, open IntelliJ IDEA to begin setting up your project.

Configuring the JDK

The Java Development Kit (JDK) is crucial for compiling and running Java applications.

  1. Install Microsoft JDK 17:
  2. Set Up the JDK in IntelliJ IDEA:
    • On the welcome screen, click on New Project.
    • Select Java and choose the installed JDK from the dropdown menu.
    • Click Next and then Finish to create your project.

Creating a New Java Project

With IntelliJ IDEA and the JDK configured, you’re ready to create your first Java project.

Initializing the Project

  1. Start a New Project:
    • Open IntelliJ IDEA and click on New Project.
  2. Select Project Type:
    • Choose Java without using Maven.
  3. Name the Project:
    • Enter HelloWorld as the project name.
  4. Configure Project Settings:
    • Ensure the appropriate JDK is selected.
    • Click Finish to create the project.

Understanding the Project Structure

Once the project is created, familiarize yourself with the following directories:

  • src/: Contains your Java source files.
  • out/: Stores compiled class files.
  • META-INF/: Holds metadata for your project, such as the manifest file.

Writing Your First Java Program

Now, let’s write a simple Java program that prints “Hello and welcome!” to the console.

Adding Sample Code

  1. Navigate to the Source Directory:
    • Expand the src/ folder in the Project Explorer.
  2. Create a New Java Class:
    • Right-click on the org.studyeasy package, select New → Java Class, and name it HelloWorld.
  3. Write the Code:

Running the Application

  1. Run the Program:
    • Click the Run button or right-click the HelloWorld class and select Run ‘HelloWorld.main()’.
  2. View the Output:
    • The console should display:

Packaging Your Application into a JAR File

Packaging your application allows you to distribute it as a standalone executable.

Creating an Artifact

  1. Navigate to Project Structure:
    • Go to File → Project Structure.
  2. Add a New Artifact:
    • Select Artifacts in the left pane.
    • Click the + icon and choose JAR → From modules with dependencies.
  3. Configure the Artifact:
    • Select the HelloWorld module.
    • Specify the Main Class (org.studyeasy.HelloWorld).
    • Click OK to create the artifact.

Configuring the Manifest

The manifest file defines entry points for your JAR.

  1. Verify Manifest Configuration:
    • Ensure the MANIFEST.MF includes the Main-Class attribute pointing to org.studyeasy.HelloWorld.
  2. Apply Changes:
    • Click Apply and then OK to save configurations.

Building the JAR File

  1. Build the Artifact:
    • Go to Build → Build Artifacts → Build.
  2. Locate the JAR:
    • The JAR file is typically found in the out/artifacts/HelloWorld_jar/ directory.
  3. Run the JAR File:
    • Right-click the JAR and select Run, or use the command line:

  1. The console will display:

Troubleshooting Common Issues

Class Not Found Exception

Issue: Running the JAR file results in a ClassNotFoundException.

Cause: The manifest file may not correctly specify the main class or the classpath is improperly configured.

Solution:

  1. Edit Run Configuration:
    • Navigate to Run → Edit Configurations.
  2. Modify Before Launch Settings:
    • In the Before launch section, click the + icon and select Build Artifacts.
    • Choose the appropriate JAR artifact.
  3. Apply and Run:
    • Click Apply and then OK.
    • Run the application again to ensure the configuration is correct.

Missing Output Folder

Issue: The out folder is not generated as expected after building the project.

Cause: Possible delays or issues with the build process, possibly due to JDK version incompatibilities.

Solution:

  1. Refresh the Project:
    • Right-click the project and select Reload from Disk.
  2. Rebuild the Project:
    • Go to Build → Rebuild Project to ensure all components are correctly compiled.
  3. Verify JDK Compatibility:
    • Ensure you’re using a compatible JDK version (Java 17 is recommended).

Conclusion

Congratulations! You’ve successfully created, run, and packaged your first Java application using IntelliJ IDEA without Maven. This foundational knowledge sets the stage for more complex projects and introduces you to the essentials of Java development.

Key Takeaways

  • Environment Setup: Proper installation and configuration of IntelliJ IDEA and JDK are crucial.
  • Project Structure: Understanding the organization of source files and compiled outputs aids in efficient development.
  • Basic Coding: Writing and running a simple Java program builds confidence and foundational skills.
  • Packaging Applications: Creating a JAR file allows for easy distribution and execution of your Java applications.





Note: This article is AI generated.

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Embark on your Java development journey with confidence, and remember that experimentation and practice are key to mastering programming. Happy coding!

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