Introduction to Java - Hello, World!

Java is a versatile and powerful programming language widely used in a variety of applications, from web development to mobile apps. In the context of FIRST Robotics Competition (FRC), Java plays a critical role in programming robots. Java is the primary language used for writing control code that drives the behavior of FRC robots, thanks to its ease of use, object-oriented design, and integration with powerful libraries and frameworks.

FRC teams (Like the FEDS!) choose Java because:

• Cross-Platform Compatibility: Java can run on different systems, meaning the same code can be developed and tested on a wide variety of machines.
• Robust Libraries: Java offers extensive libraries to handle everything from sensors to motors and communication, making it perfect for controlling complex robot systems.
• Support and Documentation: Java has been used for FRC programming for many years, and there is a large community providing support and resources to help teams.
• Object-Oriented Design: Java's object-oriented nature helps structure code in a manageable and reusable way, which is crucial when building and maintaining complex robot programs.

In this guide, we'll start with a simple introduction to Java and explain how to write a basic "Hello, World!" program to get you started.

What is Java?

Java is a high-level, object-oriented programming language designed to be simple, secure, and portable.

Why Java for FRC?

FRC teams use Java to program their robots primarily because of the WPILib library, which provides everything needed to control robot hardware (such as motors, sensors, and cameras). Java is integrated with this library, making it the go-to choice for teams who want to develop software for controlling their robots.

Your First Java Program: "Hello, World!"

Before diving into complex robot programming, let’s take a look at a basic Java program that outputs "Hello, World!" to the screen. This will help you get familiar with Java’s syntax.

Code Example

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Code Explanation

1. public class HelloWorld:

   • This line defines a class named HelloWorld. In Java, every program must be inside a class, which serves as a blueprint for creating objects.
   • public means the class is accessible to other parts of the program.

2. public static void main(String[] args):

   • This is the main method, the entry point of any Java application. When you run a Java program, the execution starts from the main method.
   • public: The method is accessible from anywhere.
   • static: The method can be called without creating an instance of the class.
   • void: The method does not return any value.
   • String[] args: This allows the program to accept arguments from the command line (we won’t use them in this simple program).

3. System.out.println("Hello, World!");:

   • This line prints the text "Hello, World!" to the console. System.out refers to the output stream (the console in this case), and println() is used to print a line of text.

Conclusion

Congratulations! You’ve just written your first Java program. While this example is simple, it demonstrates the basic structure of a Java program, including how to define classes and methods, as well as how to print output to the screen.

In FRC programming, Java is used in a similar way to control robot behavior, but with added complexity such as motor control, sensor integration, and autonomous routines. Now that you've gotten a quick introduction of Java, you're ready to move onto more java concepts and code.

Onwards in Java

We HIGHLY recommend that you take a java tutorial online like w3 School's Java Tutorial (opens in a new tab). This is going to help you GREATLY when learning and understanding the FRC Java code we sample throughout the Programming documentation.

Most of all, Happy coding!