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. This is a foundational concept in enterprise application development that professional developers rely on daily. The explanations below are written to be beginner-friendly while covering the depth and nuance that comes from real-world Java experience. Take your time with each section and practice the examples

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

Click ▶ Run to see the result

Edit the code on the left, then click Run

Java|43 lines|1290 chars|✓ Valid syntax

UTF-8

Quick Quiz: Methods

Methods & Parameters

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));
        }
    }
}

Output

Click ▶ Run to see the result

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

Topics in This Module

Methods & Parameters

Methods in Java

Try It Yourself: Utility Methods

Quick Quiz: Methods

Topics in This Module