Sarah Java Tutorial

“Hello, World!” program in Java.

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
  1. public class HelloWorld { ... }: This line defines a class named HelloWorld. In Java, classes are the building blocks of programs. Each Java program must have at least one class. The public keyword indicates that the class is accessible from other classes.
  2. public static void main(String[] args) { ... }: This line defines the main method. In Java, the main method is the entry point of a Java program. When you run a Java program, the JVM (Java Virtual Machine) starts executing the code from the main method. The public keyword indicates that the method can be accessed from outside the class. The static keyword indicates that the method belongs to the class itself, rather than to instances of the class. The return type void means that the method does not return any value. String[] args is the parameter list, which allows the program to accept command-line arguments. In this case, we’re not using the command-line arguments, so args is unused.
  3. System.out.println("Hello, World!");: This line prints the string “Hello, World!” to the console.
    • System is a pre-defined class in Java’s standard library (java.lang package) that provides access to system resources.
    • out is a static member of the System class, which is an instance of the PrintStream class. It represents the standard output stream, typically the console.
    • println() is a method of the PrintStream class that prints the specified string followed by a newline character, causing the cursor to move to the next line. In this case, it prints “Hello, World!” to the console.

So, when you run this program, it will display “Hello, World!” in the console output.

By Sarah