Nội dung kiến thức:
- OOP:
	- T/c bao đóng -> DONE
		- Thuộc tính truy xuất public/private/protected/default (friendly, internal)
		- setter/getter
	- T/c kế thừa -> DONE
		- override
		- overloading

	- T/c đa hình: 1 object -> khởi tạo từ class object
		- Đa hình là gì?
			- 1 đối tượng cụ thể
			- Liên tưởng:
				object: các bạn sinh viên
					- Bạn bè (bạn)
					- Thầy <-> trò (bạn)
					- Cha <-> con (bạn)
					- Ông <-> chau (bạn)
					- Con <-> cha (bạn)
		- Ứng dụng của đa hình trong lập trình là gì?
			- Xác định và hiệu nghiệp -> Khi nào thì nên dùng -> Khi nào thì ko???
	- T/c trừu tượng
		TH1: Khi nào thì nên đưa về abstract
			Hiểu nên dùng khi nào?
		TH2: Ý nghĩa của nó
			Yêu cầu lớp con -> Thực hiện override toàn bộ phương thức abstract của lớp cha.

	- static: Tìm hiểu về thành phần này
=============================================================================================

#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 extends Shape{
    double PI = Math.PI;
    double radius;

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

#HCN.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;

/**
 *
 * @author teacher
 */
public class HCN {
    public static double width;
    public double height;
    
    public void showTest() {
        System.out.println("Xin chao abc");
    }
    
    public static void showB() {
        System.out.println("XIn chao B");
    }
}

#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 extends Shape{
    double width;
    double height;

    public Rectangle() {
    }
    
    @Override
    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());
    }
    
    @Override
    public double getCV() {
        return 2 * (width + height);
    }
    
    @Override
    public double getS() {
        return width * height;
    }
    
    public void testing() {
        System.out.println("XIn chao testing");
    }
}

#Shape.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;

/**
 *
 * @author teacher
 */
public abstract class Shape {
    public abstract void input();
    
    public abstract double getCV();
    
    public abstract double getS();
    
    public void xinchao() {
        System.out.println("Xin chao OKOK");
    }
}

#Test.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;

/**
 *
 * @author teacher
 */
public class Test {
    public static void main(String[] args) {
//        Shape shape = new Shape(); //Binh thuong
//        shape.input();
//        shape.xinchao();
        
        Circle circle = new Circle();
        circle.input();
        System.out.println("Dien tich: " + circle.getS());
//        circle.xinchao();
//        circle.showAbc();
        
        //T/c Đa hình
//        Circle c = new Shape(); Sai -> Ko tao dc
        Shape c1 = new Circle();
        Shape c2 = new Rectangle();
        //c1, c2: Kieu du lieu la Shape
        //c1 -> khoi tao tu Circle
        //c2 -> khoi tao Rectangle
        //c1 -> doi tuong that la gi: Circle
        //c2 -> doi tuong that la gi: Rectangle
        //Che do debug -> Code
        //c1 ->Hieu la doi tuong Shape
//        c1.xinchao();
//        c1.getCV();
        
        //Che do runtime -> Running
        //c1 -> Hieu la doi tuong Circle
//        c1.showAbc();
        //Lam sao de goi showAbc()
        if(c1 instanceof Circle) {
            ((Circle) c1).showAbc();
        }
    }
}

#Test01.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.ArrayList;

/**
 *
 * @author teacher
 */
public class Test01 {
    public static void main(String[] args) {
        //Quản lý thong tin hình tròn và hcn trong 1 mảng -> dataList
        ArrayList<Circle> circles = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Circle c = new Circle();
            c.input();
            
            circles.add(c);
        }
        
        ArrayList<Rectangle> rectangles = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Rectangle r = new Rectangle();
            r.input();
            
            rectangles.add(r);
        }
        
        //Duyet qua 2 mang circles va rectangles -> tinh dien tich & chu vi
        ArrayList<Shape> dataList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            //Da hinh -> s: Kieu du lieu la Shape
            //s ->> doi tuong that la Circle
            //s -> Circle
            Shape s = new Circle();
            s.input();
            dataList.add(s);
        }
        
        for (int i = 0; i < 10; i++) {
            Shape s = new Rectangle();
            s.input();
            dataList.add(s);
        }
        
        //dataList -> Gom cac phan tu: Circle & Rectangle
        for (Shape shape : dataList) {
            System.out.println("Dien tich: " + shape.getS());
        }
    }
}

#Test2.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;

/**
 *
 * @author teacher
 */
public class Test2 {
    public static void main(String[] args) {
        HCN hcn1 = new HCN();
        HCN.width = 10;
        hcn1.height = 20;
        hcn1.showTest();
        
        HCN hcn2 = new HCN();
        System.out.println("Chieu rong: " + HCN.width + ", chieu cao: " + hcn2.height);
        HCN.width = 100;
        hcn2.height = 200;
        hcn2.showTest();
        
        System.out.println("Chieu rong: " + HCN.width + ", chieu cao: " + hcn1.height);
        System.out.println("Chieu rong: " + HCN.width + ", chieu cao: " + hcn2.height);
        
        HCN.showB();
    }
}