Methods

Syntax

returnType methodName(parameters) {\n  // code\n  return value;\n}

Breaking down the syntax

return type

The result type, or void when no value is returned.

parameters

Typed input variables for a call.

static

The method belongs to the class and has no current instance.

How it works

A method names an operation inside a class or interface. Its declaration tells callers which inputs it accepts and which result it returns.

Call

Supply arguments matching the method parameters.

Execute

Run the statements with local variables.

Return

Return a value matching the declared result type, or complete a void method.

Examples

public class Main {
  static int total(int price, int quantity) {
    return price * quantity;
  }
  public static void main(String[] args) {
    System.out.println(total(12, 3));
  }
}

public class Calculator {
    public static int add(int a, int b) {
        return a + b;
    }

    public static void main(String[] args) {
        int result = add(5, 3);
        System.out.println(result);  // 8
    }
}

public class Printer {
    public static void printGreeting(String name) {
        System.out.println("Hello, " + name + "!");
        // no return statement needed
    }

    public static void main(String[] args) {
        printGreeting("John");
    }
}

public class Greeter {
    public static String greet(String name) {
        return greet(name, "Hello");
    }

    public static String greet(String name, String greeting) {
        return greeting + ", " + name + "!";
    }

    public static void main(String[] args) {
        System.out.println(greet("John"));            // Hello, John!
        System.out.println(greet("Zain", "Hey"));       // Hey, Zain!
    }
}

public class ArrayModifier {
    public static void doubleValues(int[] numbers) {
        for (int i = 0; i < numbers.length; i++) {
            numbers[i] *= 2;
        }
    }

    public static void main(String[] args) {
        int[] values = {1, 2, 3};
        doubleValues(values);
        System.out.println(java.util.Arrays.toString(values));  // [2, 4, 6]
    }
}

Best practices

• Use void as the return type when a method performs an action but produces no result to hand back
• Keep methods focused on a single, well-defined task - if a method needs a long comment to explain what it does, consider splitting it
• Use descriptive verb-based method names (calculateTotal, not total) so a call site reads clearly
• Remember arrays and objects are passed by reference in Java, so modifying them inside a method affects the original outside it - primitives, however, are passed by value (copied)

Runtime & versions

Java Virtual Machine. Feature availability depends on the language and runtime version used by your project; consult the official reference below.

When should I use this?

Use methods to give operations clear names and keep each operation focused.

Common mistakes

An absent result

A method declared to return int must return a compatible value on every path that completes normally.

Incorrect

static int doubleValue(int n) {
  System.out.println(n * 2);
}

Corrected

static int doubleValue(int n) {
  return n * 2;
}

Compare approaches

• Instance method: Operate on a particular object’s state.
• Static method: Perform an operation without a current instance.

Explore deeper

Overloading

Methods can share a name when their parameter lists differ. The return type alone does not distinguish overloads. The compiler chooses an applicable overload using argument types and Java’s invocation rules.

Related Java documentation

Specifications & further reading

• Dev.java: defining methods