OOPsConcept.md

Encapsulation

Wrapping of data and methods in a single unit is called Encapsulation

class Sample{
    int x = 10;
    int y = 20;
}

class Demo{
    public static void main(String args[]){
        Sample obj = new Sample();
        System.out.println(obj.x);
        System.out.println(obj.y);
    }
}  // output: 10 20

A class is called encapsulated if all the data members are private and setter and getter methods are available for all the data members

class Sample{
    private int x = 10;
    private int y = 20;

    void setX(int a){
        x = a;
    }
    void setY(int b){
        y = b;
    }
    int getX(){
        return x;
    }
    int getY(){
        return y;
    }
}

class Demo{
    public static void main(String args[]){
        Sample obj = new Sample();
        obj.setX(100);
        obj.setY(200);
        System.out.println(obj.getX());
        System.out.println(obj.getY);
        // System.out.println(obj.x);  // would through an error
    }
}  // output: 100 200

POLYMORPHISM

writing the method with same name by changing the signature is called method overloading

Signature means either no of param or types of param or order of param

class Sample{
    void fun1(int a){
        System.out.println("This is fun1");
    }
    void fun1(int a, int b){
        System.out.println("This is fun2");
    }
}

class main{
    public static void main(String args[]){
        sample1 obj = obj.fun1(100);
        sample1 obj = obj.fun1(200, 300);
    }
}