Methods & Parameters

Methods are blocks of reusable code that perform specific tasks. They can accept input parameters and return output values, making your code modular and organized.

40 min•By Priygop Team•Last updated: Feb 2026

Methods in Java

Example

public class MethodsDemo {
    // Method with no parameters, no return
    static void greet() {
        System.out.println("Hello from Java!");
    }
    
    // Method with parameters
    static void greetPerson(String name) {
        System.out.println("Hello, " + name + "!");
    }
    
    // Method with return value
    static int add(int a, int b) {
        return a + b;
    }
    
    // Method with multiple parameters
    static double calculateBMI(double weight, double height) {
        return weight / (height * height);
    }
    
    // Method overloading (same name, different parameters)
    static int multiply(int a, int b) {
        return a * b;
    }
    
    static double multiply(double a, double b) {
        return a * b;
    }
    
    static int multiply(int a, int b, int c) {
        return a * b * c;
    }
    
    public static void main(String[] args) {
        // Calling methods
        greet();
        greetPerson("Alice");
        
        int sum = add(15, 25);
        System.out.println("Sum: " + sum);
        
        double bmi = calculateBMI(70, 1.75);
        System.out.println("BMI: " + String.format("%.1f", bmi));
        
        // Method overloading in action
        System.out.println("2 x 3 = " + multiply(2, 3));
        System.out.println("2.5 x 3.5 = " + multiply(2.5, 3.5));
        System.out.println("2 x 3 x 4 = " + multiply(2, 3, 4));
    }
}

Try It Yourself: Utility Methods

Try It Yourself: Utility MethodsJava

Java Editor

✓ ValidTab = 2 spaces

public class StringUtils {
    // Reverse a string
    static String reverse(String text) {
        String reversed = "";
        for (int i = text.length() - 1; i >= 0; i--) {
            reversed += text.charAt(i);
        }
        return reversed;
    }
    
    // Count vowels
    static int countVowels(String text) {
        int count = 0;
        String vowels = "aeiouAEIOU";
        for (char c : text.toCharArray()) {
            if (vowels.indexOf(c) != -1) {
                count++;
            }
        }
        return count;
    }
    
    // Check if palindrome
    static boolean isPalindrome(String text) {
        String clean = text.toLowerCase().replaceAll(" ", "");
        return clean.equals(reverse(clean).toLowerCase());
    }
    
    public static void main(String[] args) {
        String word = "Hello World";
        
        System.out.println("Original: " + word);
        System.out.println("Reversed: " + reverse(word));
        System.out.println("Vowels: " + countVowels(word));
        
        // Test palindromes
        String[] tests = {"radar", "hello", "level", "java"};
        System.out.println("\nPalindrome Check:");
        for (String test : tests) {
            System.out.println(test + " → " + isPalindrome(test));
        }
    }
}

public class StringUtils {
    // Reverse a string
    static String reverse(String text) {
        String reversed = "";
        for (int i = text.length() - 1; i >= 0; i--) {
            reversed += text.charAt(i);
        }
        return reversed;
    }
    
    // Count vowels
    static int countVowels(String text) {
        int count = 0;
        String vowels = "aeiouAEIOU";
        for (char c : text.toCharArray()) {
            if (vowels.indexOf(c) != -1) {
                count++;
            }
        }
        return count;
    }
    
    // Check if palindrome
    static boolean isPalindrome(String text) {
        String clean = text.toLowerCase().replaceAll(" ", "");
        return clean.equals(reverse(clean).toLowerCase());
    }
    
    public static void main(String[] args) {
        String word = "Hello World";
        
        System.out.println("Original: " + word);
        System.out.println("Reversed: " + reverse(word));
        System.out.println("Vowels: " + countVowels(word));
        
        // Test palindromes
        String[] tests = {"radar", "hello", "level", "java"};
        System.out.println("\nPalindrome Check:");
        for (String test : tests) {
            System.out.println(test + " → " + isPalindrome(test));
        }
    }
}

Output

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Edit the code on the left, then click Run

Java|43 lines|1290 chars|✓ Valid syntax

UTF-8

Methods & Parameters

Methods in Java

Try It Yourself: Utility Methods

Quick Quiz: Methods