The "Hello, World!" program is a classic example used to introduce beginners to programming. Here's how you can write a "Hello, World!" program in Java:

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

Let's break down this code:

• The first line declares a public class called "HelloWorld". The name of the class must match the name of the file that contains it (i.e., if you save this code in a file called "HelloWorld.java", the class should be named "HelloWorld").
• Inside the class, we declare a public static method called "main". This is the entry point of our program, and it's where the Java Virtual Machine (JVM) will start executing our code.
• The "main" method takes an array of strings as an argument, which we've named "args". We're not using this argument in our "Hello, World!" program, but it's a common way to pass command-line arguments to a Java program.
• Inside the "main" method, we use the System.out.println() method to print the string "Hello, World!" to the console.

When you run this program, you should see the message "Hello, World!" printed to the console.