The Converter

package test;

import java.util.Scanner;

class Shape{
    private double len1, len2;
    public String s;
    Shape(String msg) {
        System.out.println(msg + " is created");
        this.s = msg;
    }

    void area(double len1, double len2) {
        this.len1 = len1;
        this.len2 = len2;

        System.out.println("Area of " + s + " is : " + len1 * len2 + "\n\n");
    }

    void area(double constant, double len1, double len2) {
        this.len1 = len1;
        this.len2 = len2;

        System.out.println("Area of " + s + " is : " + constant * (len1 * len2) + "\n\n");
    }

    void area(double len1) {
        this.len1 = len1;

        System.out.println("Area of circle is : " + 3.1416 * len1 * len1 + "\n\n");
    }

    Scanner input = new Scanner(System.in);

    void resultOfTwo() {
        if(s.equals("Rectangle")) {
            System.out.println("Please Enter Length and Height");
            double a = input.nextDouble();
            double b = input.nextDouble();
            area(a, b);

        }
        else if(s.equals("Triangle")) {
            System.out.println("Please Enter Base and Height");
            double a = input.nextDouble();
            double b = input.nextDouble();
            area(.5, a, b);
        }

    }

    void resultOfCircle() {
        System.out.println("Please Enter The Radius");
        double a = input.nextDouble();
        area(a);
    }

}


public class Test {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        while(true) {

            System.out.println("Please Enter your choice : ");
            System.out.println("1. Calculate Rectangle's Area");
            System.out.println("2. Calculate Triangle's Area");
            System.out.println("3. Calculate Circle's Area");
            System.out.println("4. Exit");

            int choice = input.nextInt();

            if (choice == 1) {

                Shape ob = new Shape("Rectangle");
                ob.resultOfTwo();

            } else if (choice == 2) {

                Shape ob = new Shape("Triangle");
                ob.resultOfTwo();

            } else if (choice == 3) {

                Shape ob = new Shape("Circle");
                ob.resultOfCircle();

            } else if(choice == 4) {

                break;

            } else {
                System.out.println("Your choice is wrong. Please try again!\n\n");
            }

        }

    }
}