Functions in Java

20 min readJul 14, 2025

About Functions:- A function is a block of code that performs a specific task. It is used for reusability and code organization.

A block of Code Means:-A collection of statements that are written inside curly brackets { } and execute together.

Why use:-There are many reasons using Functions.

Code Reusability :- Write once, use multiple times without rewriting code.
Modularity:- Break large programs into smaller, manageable parts.
Readability:- Makes the code cleaner and easier to understand.
Maintainability:- Easier to modify and fix specific parts of the code.
Avoid Repetition:- Prevents duplication by using functions for repetitive tasks.
Better Debugging:- Easier to find and fix errors in smaller function blocks.
Scalability:- Helps in handling larger projects by organizing the logic efficiently.

Type Of Functions:- There are main two types of Functions.

a. Library Function
b. User-defined Function

User-Defined Function:- Functions created by the user to perform specific tasks.

Type Of User-defined Functions:- There are mainly four types of Functions.

a. No Parameters with No Return Type function
b. Parameters with No Return Type function
c. No Parameters with Return Type function
d. Parameters with Return Type function

No Parameters with No Return Type function:- A user-defined function that has neither parameters nor a return value is called a No Parameters with No Return Type Function.

Syntax:-
1. `public static void functionName()`

public static void functionName() {
    // Statements
}

public → Accessible from anywhere (any class or package).
static → Can be called without creating an object.
void → Does not return any value.
Most commonly used in main() methods and utility/helper functions.

Examples:-

1. 
public class Main{

    public static void printWelcome() {
        System.out.println("Welcome to Java!");
    }

    public static void main(String[] args) {
        printWelcome(); 
    }
}
// Output: Welcome to Java!
2.
public class Main{

    public static void printRaman() {
        System.out.println("Welcome to Raman!");
    }

    public static void main(String[] args) {
        printWelcome(); 
    }
}
// Output: Welcome to Raman!
3.
public class Main{

    public static void printEvenNumbers() {
        for (int i = 1; i <= 10; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is a even number");
            }
           else{
               System.out.println(i + " is an odd number");
            }
    }

    public static void main(String[] args) {
        printEvenNumbers();
    }
}
//outputs:
// 1 is an odd number
// 2 is a even number
// 3 is an odd number
// 4 is a even number
// 5 is an odd number
// 6 is a even number
// 7 is an odd number
// 8 is a even number
// 9 is an odd number
// 10 is a even number

4. 
public class Main{

    public static void showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        showNames();
    }
}
// outputs:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main{

    public static void displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        displayMarks();
    }
}
// outputs:
// Ajay: 85
// Raman: 90
// Kumar: 80

2. static `void functionName()`

static void functionName() {
    // Statements
}

static → Can be called without creating an object.
No access modifier → Default access (package-private); available only within the same package.
void → Does not return any value.
Commonly used for internal utility methods or within the same class.

Examples:-

1.
public class Main {

    static void printWelcome() {
        System.out.println("Welcome to Java!");
    }

    public static void main(String[] args) {
        printWelcome();
    }
}
// Output: Welcome to Java!

2. 
public class Main {

    static void printRaman() {
        System.out.println("Welcome to Raman!");
    }

    public static void main(String[] args) {
        printRaman();
    }
}
// Output: Welcome to Raman!
3. 
public class Main {

    static void printEvenNumbers() {
        for (int i = 1; i <= 10; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is a even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        printEvenNumbers();
    }
}
// Outputs:
// 1 is an odd number
// 2 is a even number
// 3 is an odd number
// 4 is a even number
// 5 is an odd number
// 6 is a even number
// 7 is an odd number
// 8 is a even number
// 9 is an odd number
// 10 is a even number
4. 
public class Main {

    static void showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        showNames();
    }
}
// Outputs:
// Raman
// Ajay
// Kumar
5. 
import java.util.HashMap;
import java.util.Map;

public class Main {

    static void displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        displayMarks();
    }
}
// Outputs:
// Ajay: 85
// Raman: 90
// Kumar: 80

3. public `void functionName()`

public void functionName() {
    // Statements
}

public → The method is accessible from anywhere (any class or package).
No static → Must be called using an object of the class.
void → Does not return any value.
Commonly used in object-oriented programming for instance behavior (not in main() unless called via an object).

Examples:-

1. 
public class Main {

    public void printWelcome() {
        System.out.println("Welcome to Java!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printWelcome();
    }
}
// Output: Welcome to Java!

2. 
public class Main {

    public void printRaman() {
        System.out.println("Welcome to Raman!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printRaman();
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    public void printEvenNumbers() {
        for (int i = 1; i <= 10; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is a even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printEvenNumbers();
    }
}
// Output:
// 1 is an odd number
// 2 is a even number
// ...
// 10 is a even number

4. 
public class Main {

    public void showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.showNames();
    }
}
// Output:
// Raman
// Ajay
// Kumar
5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public void displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.displayMarks();
    }
}
// Output (order may vary):
// Ajay: 85
// Raman: 90
// Kumar: 80

4. `void functionName()`

void functionName() {
    // Statements
}

No access modifier → Default access (package-private); accessible only within the same package.
No static → Must be called using an object.
void → Does not return any value.
Mostly used for internal methods when external access is not required.

Examples:-

1.
public class Main {

    void printWelcome() {
        System.out.println("Welcome to Java!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printWelcome();
    }
}
// Output:
// Welcome to Java!
2.
public class Main {

    void printRaman() {
        System.out.println("Welcome to Raman!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printRaman();
    }
}
// Output:
// Welcome to Raman!
3.
public class Main {

    void printEvenNumbers() {
        for (int i = 1; i <= 10; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is a even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printEvenNumbers();
    }
}
// Output:
// 1 is an odd number
// 2 is a even number
// ...
// 10 is a even number
4.
public class Main {

    void showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.showNames();
    }
}
// Output:
// Raman
// Ajay
// Kumar
5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    void displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.displayMarks();
    }
}
// Output (order may vary):
// Ajay: 85
// Raman: 90
// Kumar: 80

Parameters:- Parameters are variables or fields that take input when a function is called. They are defined inside the function’s parentheses ().

Arguments:- Arguments are the actual values that are passed to parameters when a function is called. They are provided inside the function’s parentheses ().

Examples:-

public class Main {

    // Function with a parameter
    static void users(String name) { // 'name' is a Parameter
        System.out.println("Hello, " + name);
    }

    public static void main(String[] args) {
        // Function call with an argument
        users("Raman");  // "Raman" is the argument
    }
}

Parameters with No Return Type:- A user-defined function that has parameters but does not return any value is called a Parameters with No Return Type Function.

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Syntax:-
1. public static void functionName(Parameters)

public static void functionName(type parameter1, type parameter2, ...) {
    // Statements
}

Examples:-

1. 
public class Main {

    public static void printWelcome(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        printWelcome("Java");
    }
}
// Output: Welcome to Java!

2. 
public class Main {

    public static void printRaman(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        printRaman("Raman");
    }
}
// Output: Welcome to Raman!

3. 
public class Main {

    public static void printEvenNumbers(int start, int end) {
        for (int i = start; i <= end; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is an even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        printEvenNumbers(1, 10);
    }
}
// Output:
// 1 is an odd number
// 2 is an even number
// ...
// 10 is an even number

4. 
public class Main {

    public static void showNames(String[] names) {
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        String[] names = {"Raman", "Ajay", "Kumar"};
        showNames(names);
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static void displayMarks(Map<String, Integer> marks) {
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        displayMarks(marks);
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

2. static `void functionName(Parameters)`

Syntaxt

static void functionName(type parameter1, type parameter2, ...) {
    // Statements
}

Examples:-

1. 
public class Main {

    static void printWelcome(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        printWelcome("Java");
    }
}
// Output: Welcome to Java!

2. 
public class Main {

    static void printRaman(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        printRaman("Raman");
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    static void printEvenNumbers(int start, int end) {
        for (int i = start; i <= end; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is an even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        printEvenNumbers(1, 10);
    }
}
// Output:
// 1 is an odd number
// ...
// 10 is an even number

4.
public class Main {

    static void showNames(String[] names) {
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        String[] names = {"Raman", "Ajay", "Kumar"};
        showNames(names);
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    static void displayMarks(Map<String, Integer> marks) {
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        displayMarks(marks);
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

3. public `void functionName(Parameters)`

Syntax

public void functionName(type parameter1, type parameter2, ...) {
    // Statements
}

Examples:-

1.
public class Main {

    public void printWelcome(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printWelcome("Java");
    }
}
// Output: Welcome to Java!

2.
public class Main {

    public void printRaman(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printRaman("Raman");
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    public void printEvenNumbers(int start, int end) {
        for (int i = start; i <= end; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is an even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printEvenNumbers(1, 10);
    }
}
// Output:
// 1 is an odd number
// ...
// 10 is an even number

4.
public class Main {

    public void showNames(String[] names) {
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        String[] names = {"Raman", "Ajay", "Kumar"};
        obj.showNames(names);
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public void displayMarks(Map<String, Integer> marks) {
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        obj.displayMarks(marks);
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

4. `void functionName(Parameters)`

void functionName(type parameter1, type parameter2, ...) {
    // Statements
}

Examples:-

1.
public class Main {

    void printWelcome(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printWelcome("Java");
    }
}
// Output: Welcome to Java!

2.
public class Main {

    void printRaman(String name) {
        System.out.println("Welcome to " + name + "!");
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printRaman("Raman");
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    void printEvenNumbers(int start, int end) {
        for (int i = start; i <= end; i++) {
            if (i % 2 == 0) {
                System.out.println(i + " is an even number");
            } else {
                System.out.println(i + " is an odd number");
            }
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        obj.printEvenNumbers(1, 10);
    }
}
// Output:
// 1 is an odd number
// ...
// 10 is an even number

4. 
public class Main {

    void showNames(String[] names) {
        for (String name : names) {
            System.out.println(name);
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        String[] names = {"Raman", "Ajay", "Kumar"};
        obj.showNames(names);
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    void displayMarks(Map<String, Integer> marks) {
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }

    public static void main(String[] args) {
        Main obj = new Main();
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        obj.displayMarks(marks);
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

About Return:- The return keyword is used to send back the result or final value of a function. When return is executed, the function stops at that point and returns a value.

No Parameters with Return Type:- A user-defined function that has no parameters but returns a value is called a No Parameters with Return Type Function.

Syntax:-
1. public static type functionName()

public static returnType functionName() {
    // Statements
    return value; // only if returnType is not void
}

Examples:-

1.
public class Main {

    public static String printWelcome() {
        return "Welcome to Java!";
    }

    public static void main(String[] args) {
        System.out.println(printWelcome());
    }
}
// Output: Welcome to Java!

2.
public class Main {

    public static String printRaman() {
        return "Welcome to Raman!";
    }

    public static void main(String[] args) {
        System.out.println(printRaman());
    }
}
// Output: Welcome to Raman!
3.
public class Main {

    public static String printEvenNumbers() {
        String result = "";
        for (int i = 1; i <= 10; i++) {
            if (i % 2 == 0) {
                result += i + " is an even number\n";
            } else {
                result += i + " is an odd number\n";
            }
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(printEvenNumbers());
    }
}
// Output:
// 1 is an odd number
// 2 is an even number
// ...
// 10 is an even number

4.
public class Main {

    public static String showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(showNames());
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static String displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(displayMarks());
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

2. static type functionName()

static returnType functionName() {
    // Statements
    return value;
}

Examples:-

1.
public class Main {

    static String printWelcome() {
        return "Welcome to Java!";
    }

    public static void main(String[] args) {
        System.out.println(printWelcome());
    }
}
// Output: Welcome to Java!

2.
public class Main {

    static String printRaman() {
        return "Welcome to Raman!";
    }

    public static void main(String[] args) {
        System.out.println(printRaman());
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    static String printEvenNumbers() {
        String result = "";
        for (int i = 1; i <= 10; i++) {
            if (i % 2 == 0) {
                result += i + " is an even number\n";
            } else {
                result += i + " is an odd number\n";
            }
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(printEvenNumbers());
    }
}
// Output:
// 1 is an odd number
// ...
// 10 is an even number

4.
public class Main {

    static String showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(showNames());
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    static String displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(displayMarks());
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

3. public type functionName()

public returnType functionName() {
    // Statements
    return value; 
}

Examples:-

1.
public class Main {

    public String printWelcome() {
        return "Welcome to Java!";
    }

    public static void main(String[] args) {
        Main obj = new Main(); 
        System.out.println(obj.printWelcome());
    }
}
// Output: Welcome to Java!

2.
public class Main {

    public String printRaman() {
        return "Welcome to Raman!";
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.println(obj.printRaman());
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    public String printEvenNumbers() {
        String result = "";
        for (int i = 1; i <= 10; i++) {
            result += (i % 2 == 0)
                ? i + " is an even number\n"
                : i + " is an odd number\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.printEvenNumbers());
    }
}
// Output:
// 1 is an odd number
// 2 is an even number
// ...
// 10 is an even number

4.
public class Main {

    public String showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.showNames());
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public String displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.displayMarks());
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

4. type functionName()

 returnType functionName() {
    // Statements
    return value; 
}

Examples:-

1.
class Main {

    String printWelcome() {
        return "Welcome to Java!";
    }

    public static void main(String[] args) {
        Main obj = new Main();  // object needed
        System.out.println(obj.printWelcome());
    }
}
// Output: Welcome to Java!

2.
class Main {

    String printRaman() {
        return "Welcome to Raman!";
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.println(obj.printRaman());
    }
}
// Output: Welcome to Raman!
3.
class Main {

    String printEvenNumbers() {
        String result = "";
        for (int i = 1; i <= 10; i++) {
            result += (i % 2 == 0)
                    ? i + " is an even number\n"
                    : i + " is an odd number\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.printEvenNumbers());
    }
}
// Output:
// 1 is an odd number
// 2 is an even number
// ...
// 10 is an even number

4.
class Main {

    String showNames() {
        String[] names = {"Raman", "Ajay", "Kumar"};
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.showNames());
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

class Main {

    String displayMarks() {
        Map<String, Integer> marks = new HashMap<>();
        marks.put("Ajay", 85);
        marks.put("Raman", 90);
        marks.put("Kumar", 80);

        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.displayMarks());
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

Parameters with Return Type:- A user-defined function that has parameters and also returns a value is called a Parameters with Return Type Function.

Syntax:-
1. public static type functionName(Parameters)

public static returnType functionName(ParameterType parameterName) {
    // Statements
    return value; 
}

Examples:-

1.
public class Main {

    public static String printWelcome(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        System.out.println(printWelcome("Java"));
    }
}
// Output: Welcome to Java!


2.
public class Main {

    public static String printRaman(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        System.out.println(printRaman("Raman"));
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    public static String printEvenNumbers(int limit) {
        String result = "";
        for (int i = 1; i <= limit; i++) {
            if (i % 2 == 0) {
                result += i + " is an even number\n";
            } else {
                result += i + " is an odd number\n";
            }
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(printEvenNumbers(10));
    }
}
// Output:
// 1 is an odd number
// ...
// 10 is an even number

4.
public class Main {

    public static String showNames(String[] names) {
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        String[] nameList = {"Raman", "Ajay", "Kumar"};
        System.out.print(showNames(nameList));
    }
}
// Output:
// Raman
// Ajay
// Kumar
5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static String displayMarks(Map<String, Integer> marks) {
        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Map<String, Integer> studentMarks = new HashMap<>();
        studentMarks.put("Ajay", 85);
        studentMarks.put("Raman", 90);
        studentMarks.put("Kumar", 80);

        System.out.print(displayMarks(studentMarks));
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

    public static void main(String[] args) {
        System.out.print(displayMarks());
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

2. static returnType functionName(Parameters)

static returnType functionName(ParameterType parameterName) {
    // Statements
    return value;
}

Examples:-

1.
public class Main {

    static String printWelcome(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        System.out.println(printWelcome("Java"));
    }
}
// Output: Welcome to Java!

2.
public class Main {

    static String printRaman(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        System.out.println(printRaman("Raman"));
    }
}
// Output: Welcome to Raman!
3.
public class Main {

    static String printEvenNumbers(int limit) {
        String result = "";
        for (int i = 1; i <= limit; i++) {
            if (i % 2 == 0) {
                result += i + " is an even number\n";
            } else {
                result += i + " is an odd number\n";
            }
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.print(printEvenNumbers(10));
    }
}
// Output:
// 1 is an odd number
// ...
// 10 is an even number
4.
public class Main {

    static String showNames(String[] names) {
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        String[] namesArray = {"Raman", "Ajay", "Kumar"};
        System.out.print(showNames(namesArray));
    }
}
// Output:
// Raman
// Ajay
// Kumar

import java.util.HashMap;
import java.util.Map;

public class Main {

    static String displayMarks(Map<String, Integer> marks) {
        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Map<String, Integer> studentMarks = new HashMap<>();
        studentMarks.put("Ajay", 85);
        studentMarks.put("Raman", 90);
        studentMarks.put("Kumar", 80);

        System.out.print(displayMarks(studentMarks));
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

3. public type functionName(Parameters)

public returnType functionName(ParameterType parameterName){
    // Statements
    return value; 
}

Examples:-

1.
public class Main {

    public String printWelcome(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        Main obj = new Main(); 
        System.out.println(obj.printWelcome("Java"));
    }
}
// Output: Welcome to Java!

public class Main {

    public String printRaman(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.println(obj.printRaman("Raman"));
    }
}
// Output: Welcome to Raman!

3.
public class Main {

    public String printEvenNumbers(int limit) {
        String result = "";
        for (int i = 1; i <= limit; i++) {
            result += (i % 2 == 0)
                ? i + " is an even number\n"
                : i + " is an odd number\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.printEvenNumbers(10));
    }
}
// Output: 1 is an odd number ... 10 is an even number

4.
public class Main {

    public String showNames(String[] names) {
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        String[] nameList = {"Raman", "Ajay", "Kumar"};
        System.out.print(obj.showNames(nameList));
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

public class Main {

    public String displayMarks(Map<String, Integer> marks) {
        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        Map<String, Integer> studentMarks = new HashMap<>();
        studentMarks.put("Ajay", 85);
        studentMarks.put("Raman", 90);
        studentMarks.put("Kumar", 80);

        System.out.print(obj.displayMarks(studentMarks));
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

4. type functionName(Parameters)

returnType functionName(ParameterType ParameterName,...) {
    // Statements
    return value; 
}

Examples:-

1.
class Main {

    String printWelcome(String name) {
        return "Welcome to " + name + "!";
    }

    public static void main(String[] args) {
        Main obj = new Main(); 
        System.out.println(obj.printWelcome("Java"));
    }
}
// Output: Welcome to Java!

2.
class Main {

    String printRaman(String personName) {
        return "Welcome to " + personName + "!";
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.println(obj.printRaman("Raman"));
    }
}
// Output: Welcome to Raman!

3.
class Main {

    String printEvenNumbers(int range) {
        String result = "";
        for (int i = 1; i <= range; i++) {
            result += (i % 2 == 0)
                ? i + " is an even number\n"
                : i + " is an odd number\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        System.out.print(obj.printEvenNumbers(10));
    }
}
// Output:
// 1 is an odd number
// 2 is an even number
// ...
// 10 is an even number

4.
class Main {

    String showNames(String[] names) {
        String result = "";
        for (String name : names) {
            result += name + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        String[] myNames = {"Raman", "Ajay", "Kumar"};
        System.out.print(obj.showNames(myNames));
    }
}
// Output:
// Raman
// Ajay
// Kumar

5.
import java.util.HashMap;
import java.util.Map;

class Main {

    String displayMarks(Map<String, Integer> marks) {
        String result = "";
        for (Map.Entry<String, Integer> entry : marks.entrySet()) {
            result += entry.getKey() + ": " + entry.getValue() + "\n";
        }
        return result;
    }

    public static void main(String[] args) {
        Main obj = new Main();
        Map<String, Integer> studentMarks = new HashMap<>();
        studentMarks.put("Ajay", 85);
        studentMarks.put("Raman", 90);
        studentMarks.put("Kumar", 80);

        System.out.print(obj.displayMarks(studentMarks));
    }
}
// Output:
// Ajay: 85
// Raman: 90
// Kumar: 80

Functions in Java

Syntax:-1. public static void functionName()

2. static void functionName()

3. public void functionName()

4. void functionName()

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2. static void functionName(Parameters)

3. public void functionName(Parameters)

4. void functionName(Parameters)

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Syntax:-
1. `public static void functionName()`

2. static `void functionName()`

3. public `void functionName()`

4. `void functionName()`

2. static `void functionName(Parameters)`

3. public `void functionName(Parameters)`

4. `void functionName(Parameters)`