Java Learning Series | Constructors, Methods & Method Overloading

Concepts Practiced

• Class & Objects
• Instance Variables
• Static Variable
• Constructors
• Constructor Overloading
• this Keyword
• Methods
• Method Parameters
• Method Overloading
• Compile-Time Polymorphism
• Return Type & return Keyword
• Static & Non-Static Methods
• Calling Methods using Objects
• Separate Methods for GPay, Cash & Card

Code:

public class Supermarket{

    static String supermarketName = "Grace";

    String productName;
    int price;
    int quantity;

    //creating multiple constructors with same class name and different parameter list
    public Supermarket(String productName){
        this.productName = productName;
//        this.quantity = quantity;
}

    public Supermarket(String productName, int price, int quantity){
        this.productName = productName;
        this.price = price;
        this.quantity = quantity;
}

    public Supermarket(String productName, int price)
{
        this.productName = productName;
        this.price = price;
    }

    public static void main(String[] args){
//        System.out.println("Hello World");
        Supermarket product1 = new Supermarket("milk");
        Supermarket product2 = new Supermarket("curd", 20);
        Supermarket product3 = new Supermarket("Biscuit", 10, 3);

        product1.buy();
        product2.buy(30);
        product3.buy(20,"Hi");

        //calling non-static return type function
        int finalPrice = product1.buy(50,5);
        System.out.println("finalPrice: "+finalPrice);

        //calling gpay, cash, card methods
        product3.gpay(200);
        product3.cash(100);
        product3.card(500);

}

    //creating multiple methods with same method name with different parameters list in the same class
    public void buy(){
//        System.out.println("Buy Method");

}

public void buy(int account){
//        System.out.println("Buy Method - account");
//        System.out.println(this.price);
}
public void buy(int i, String payName){
//        System.out.println("Buy Method");
}

//creating method with return type
public int buy(int price, int discount){
    int total = price - discount;
    return total;
}

//creating method for gpay
public void gpay(int amount){
    System.out.println("Payment via Gpay");
    System.out.println("Amount: "+ amount);
}

//creating method for cash
public void cash(int amount){
    System.out.println("Payment via Cash");
    System.out.println("Amount: "+ amount);
}

//creating method for card
public void card(int amount){
    System.out.println("Payment via Card");
    System.out.println("Amount: "+ amount);
}

}

Output:

finalPrice: 45
Payment via Gpay
Amount: 200
Payment via Cash
Amount: 100
Payment via Card
Amount: 500