Java Basic- OOP - Tạo máy tính cơ bản calculator trong java

#Main.java

/*
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 */
package lesson05.bt986;

import java.util.Scanner;

/**
 *
 * @author Diep.Tran
 */
public class Main {

    public static void main(String[] args) {
        Calculator cal = new Calculator();

        Scanner scan = new Scanner(System.in);
        int choose;

//        System.out.println("Tong: " + cal.cong(x, y));
//        System.out.println("Hieu: " + cal.tru(x, y));
//        System.out.println("Tich: " + cal.nhan(x, y));
//        System.out.println("Thuong: " + cal.chia(x, y));
        do {
            showMenu();
            choose = scan.nextInt();
            if(choose == 5) break;

            System.out.println("Nhap x: ");
            int x = scan.nextInt();

            System.out.println("Nhap y: ");
            int y = scan.nextInt();

            switch (choose) {
                case 1:
                    System.out.println("Tong: " + cal.cong(x, y));
                    break;
                case 2:
                    System.out.println("Hieu: " + cal.tru(x, y));
                    break;
                case 3:
                    System.out.println("Tich: " + cal.nhan(x, y));
                    break;
                case 4:
                    System.out.println("Thuong: " + cal.chia(x, y));
                    break;
//                case 5:
//                    System.out.println("Thoat!!!");
//                    break;
                default:
                    System.out.println("Nhap lai!!!");
                    break;
            }
        } while (choose != 5);
    }

    static void showMenu() {
        System.out.println("1. Cong");
        System.out.println("2. Tru");
        System.out.println("3. Nhan");
        System.out.println("4. Chia");
        System.out.println("5. Thoat");
        System.out.println("Chon: ");
    }
}

#Calculator.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package lesson05.bt986;

/**
 *
 * @author Diep.Tran
 */
public class Calculator {
    public float cong(float x, float y) {
        return x + y;
    }
    public float tru(float x, float y) {
        return x - y;
    }
    public float nhan(float x, float y) {
        return x * y;
    }
    public float chia(float x, float y) {
        if(y == 0) {
            System.out.println("Yeu cau y khac 0!!!");
            return 0;
        }
        return x / y;
    }
}