Java Basic- OOP - Chu vi và diện hình hình tròn & hình chữ nhật

#Circle.java

/*
 * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */
package com.gokisoft.c2209i.bt985;

import java.util.Scanner;

/**
 *
 * @author teacher
 */
public class Circle {
    double PI = Math.PI;
    double radius;

    public Circle() {
    }
    
    public double getPI() {
        return PI;
    }
    
    public void input() {
        Scanner scan = new Scanner(System.in);
        System.out.println("Nhap ban kinh: ");
        radius = Double.parseDouble(scan.nextLine());
    }
    
    public double getCV() {
        return 2 * PI * radius;
    }
    
    public double getS() {
        return PI * radius * radius;
    }
}

#Main.java

/*
 * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */
package com.gokisoft.c2209i.bt985;

import java.util.Scanner;

/**
 *
 * @author teacher
 */
public class Main {
    public static void main(String[] args) {
        Circle circle = new Circle();
        Rectangle hcn = new Rectangle();
        int choose;
        Scanner scan = new Scanner(System.in);
        
        do {
            showMenu();
            choose = Integer.parseInt(scan.nextLine());
            
            switch (choose) {
                case 1:
                    System.out.println("Nhap dien tich hinh tron");
                    circle.input();
                    break;
                case 2:
                    double cv = circle.getCV();
                    System.out.println("Chu vi hinh tron: " + cv);
                    break;
                case 3:
                    double s = circle.getS();
                    System.out.println("Dien tich hinh tron: " + s);
                    break;
                case 4:
                    System.out.println("Nhap thong tin HCN");
                    hcn.input();
                    break;
                case 5:
                    double cvHcn = hcn.getCV();
                    System.out.println("Chu vi HCN: " + cvHcn);
                    break;
                case 6:
                    double sHcn = hcn.getS();
                    System.out.println("Dien tich HCN: " + sHcn);
                    break;
                case 7:
                    System.out.println("Thoat!!!");
                    break;
                default:
                    System.out.println("Nhap sai!!!");
                    break;
            }
        } while(choose != 7);
    }
    
    static void showMenu() {
        System.out.println("1. Nhap thong tin hinh tron");
        System.out.println("2. Tinh CV Hinh Tron");
        System.out.println("3. Tinh S Hinh Tron");
        System.out.println("4. Nhap thong tin HCN");
        System.out.println("5. Tinh CV HCN");
        System.out.println("6. Tinh S HCN");
        System.out.println("7. Thoat");
        System.out.println("Chon: ");
    }
}

#Rectangle.java

/*
 * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */
package com.gokisoft.c2209i.bt985;

import java.util.Scanner;

/**
 *
 * @author teacher
 */
public class Rectangle {
    double width;
    double height;

    public Rectangle() {
    }
    
    public void input() {
        Scanner scan = new Scanner(System.in);
        System.out.println("Nhap chieu dai: ");
        width = Double.parseDouble(scan.nextLine());
        System.out.println("Nhap chieu rong: ");
        height = Double.parseDouble(scan.nextLine());
    }
    
    public double getCV() {
        return 2 * (width + height);
    }
    
    public double getS() {
        return width * height;
    }
}