Java Class Methods

Class methods are functions defined inside a class that describe the behavior or actions of objects. They operate on class attributes or perform specific tasks.

1. Method Syntax

modifier → public, private, static, etc.
returnType → data type of value returned (void if nothing is returned)
methodName → name of the method
parameters → optional input values

2. Example 1: Instance Method

class Car {
String brand;
int year;

// Instance method
void displayInfo() {
System.out.println("Brand: " + brand + ", Year: " + year);
}
}

public class Main {
public static void main(String[] args) {
Car car1 = new Car();
car1.brand = "Toyota";
car1.year = 2022;
car1.displayInfo(); // Calling instance method

Car car2 = new Car();
car2.brand = "Honda";
car2.year = 2023;
car2.displayInfo();
}
}

class Car {

String brand;

int year;

// Instance method

void displayInfo() {

System.out.println("Brand: " + brand + ", Year: " + year);

}

public class Main {

public static void main(String[] args) {

Car car1 = new Car();

car1.brand = "Toyota";

car1.year = 2022;

car1.displayInfo(); // Calling instance method

Car car2 = new Car();

car2.brand = "Honda";

car2.year = 2023;

car2.displayInfo();

}

📌 Output:

Instance methods operate on instance variables and require objects to be called.

3. Example 2: Static Method

class MathOperations {
static int add(int a, int b) { // static method
return a + b;
}
}

public class Main {
public static void main(String[] args) {
int sum = MathOperations.add(5, 10); // No object needed
System.out.println("Sum = " + sum);
}
}

class MathOperations {

static int add(int a, int b) { // static method

return a + b;

}

public class Main {

public static void main(String[] args) {

int sum = MathOperations.add(5, 10); // No object needed

System.out.println("Sum = " + sum);

}

📌 Output:

Static methods belong to the class, not the object, and can be called using the class name.

4. Example 3: Method with Parameters and Return Value

class Calculator {
int multiply(int a, int b) { // instance method
return a * b;
}
}

public class Main {
public static void main(String[] args) {
Calculator calc = new Calculator();
int product = calc.multiply(4, 5); // passing parameters
System.out.println("Product = " + product);
}
}

class Calculator {

int multiply(int a, int b) { // instance method

return a * b;

}

public class Main {

public static void main(String[] args) {

Calculator calc = new Calculator();

int product = calc.multiply(4, 5); // passing parameters

System.out.println("Product = " + product);

}

📌 Output:

5. Example 4: Method Calling Another Method

class Person {
String name;

void greet() {
printName();
System.out.println("Welcome!");
}

void printName() {
System.out.println("Hello, " + name);
}
}

public class Main {
public static void main(String[] args) {
Person p = new Person();
p.name = "Alice";
p.greet();
}
}

class Person {

String name;

void greet() {

printName();

System.out.println("Welcome!");

}

void printName() {

System.out.println("Hello, " + name);

}

public class Main {

public static void main(String[] args) {

Person p = new Person();

p.name = "Alice";

p.greet();

}

📌 Output:

6. Key Points About Class Methods

Feature	Instance Method	Static Method
Belongs to	Object	Class
Access instance variables?	Yes	No (only static variables)
Call syntax	object.method()	Class.method()
Can be overridden	Yes	No (cannot override static methods)

Methods define object behavior.
Instance methods need objects; static methods do not.
Methods can have parameters and return values.

Java Class Methods