Writing A Basic Java Program

Introduction

Before diving into Java programming, there are key points every beginner should understand. These foundational concepts will help you understand the structure and requirements of any Java program you write.

Key Points to Note

  • All Java code must be written inside a class:

    In Java, everything revolves around classes and any code you write must be placed within a class.

  • The main() method is essential for execution:

    For your Java code to run, it must be placed in the main() method, or be called from it. The main() method serves as the entry point for your application and is required for the execution of any program.

  • Class names must match file names:

    In Java, the name of a public class must match the name of the file it's in. For example, if your class is named FirstProgram, it should be saved as FirstProgram.java. This naming convention is crucial for your code to compile and run correctly.

Note: If terms like "classes", "methods" and “public” seem unfamiliar, don't worry. We will cover these in depth in future topics.

Choosing the Right Environment for Writing Java Code

When it comes to writing Java, you have several options depending on your environment:

  • Workplace Environment:

    In a professional setting, your choice of software may be limited by the tools your organization is licensed to use. Integrated Development Environments (IDEs) are common choices because they offer features like debugging, autocompletion, and error highlighting.

  • Personal Projects:

    If you're coding at home, you have more flexibility. One common tool is IntelliJ IDEA, which you can download here. There are also online editors like JDoodle, which allow you to write and execute Java code without installing anything on your computer.

Writing Your First Java Program

A classic example for beginners is to write a program that prints a line of text to the screen. We'll go a step further and print multiple lines to give you a bit more practice.

Pseudocode Outline

Before jumping into the code, let's outline the program using pseudocode:

  1. Greet the user

  2. Inform the user of the program's purpose

  3. Thank the user for running the program

Implementing the Program in Java

Now that you have a clear outline, you can create a new class named FirstProgram and ensure the code is placed within the main() method for execution. In order to print text to the screen you can make use of the System.out.println() method.

public class FirstProgram {
    public static void main(String[] args) {
        System.out.println("Hello there!");
        System.out.println("This is a basic program to print messages to the screen.");
        System.out.println("Thank you for running this program, goodbye.");
    }
  }

Conclusion

Even though the code is simple, using pseudocode for your first Java program helps you build a strong coding foundation. As your programs grow in complexity, having a clear structure from the beginning can make the coding process much smoother and more manageable. In this case, the pseudocode served as a basic guide, ensuring that each step was clear before moving on to the actual code. As you continue to develop more complex programs, this approach will become increasingly valuable.