Java Methods

Why methods matter

Imagine you need to print a welcome banner in five different places in your program. Without methods, you would copy the same lines five times. With a method, you write the banner once and call its name whenever you need it. This is often called the DRY principle: Don't Repeat Yourself.

• Reuse: write the logic once, call it anywhere.
• Readability: a good method name explains what the code does.
• Maintenance: fix a bug in one place instead of many.
• Organization: split a large task into small, focused steps.

Creating a method

In Java, methods are defined inside a class. A method has a return type, a name, a pair of parentheses for parameters, and a body enclosed in curly braces. The keyword static means the method belongs to the class itself, so you can call it without first creating an object. The word void means the method does not send any value back.

public class Main {
  // Define a method named greet
  static void greet() {
    System.out.println("Welcome to Java!");
  }

  public static void main(String[] args) {
    greet(); // Call the method
    greet(); // Call it again
  }
}

// Output:
// Welcome to Java!
// Welcome to Java!

Notice that main is itself a method. It is the special method Java runs first when your program starts. When you call greet(), the program jumps into the greet method, runs its body, and then returns to the exact spot where it was called.

Calling a method many times

public class Main {
  static void drawLine() {
    System.out.println("------------------------");
  }

  public static void main(String[] args) {
    drawLine();
    System.out.println("Monthly Report");
    drawLine();
  }
}

// Output:
// ------------------------
// Monthly Report
// ------------------------