Java Basic- OOP - Interface - Hình chữ nhật trong java

#HCNInterface.java

/*
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 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */
package com.gokisoft.lesson06.bt995;

/**
 *
 * @author diepvan
 */
public interface HCNInterface {
    double dientichHCN();
    double getChieuDai();
    double getChieuRong();
    void setDaiRong(double cd, double cr);
}

#HinhChuNhat.java

/*
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 */
package com.gokisoft.lesson06.bt995;

/**
 *
 * @author diepvan
 */
public class HinhChuNhat implements HCNInterface{
    double chieudai, chieurong;

    @Override
    public double dientichHCN() {
        return chieudai * chieurong;
    }

    @Override
    public double getChieuDai() {
        return chieudai;
    }

    @Override
    public double getChieuRong() {
        return chieurong;
    }

    @Override
    public void setDaiRong(double cd, double cr) {
        this.chieudai = cd;
        this.chieurong = cr;
    }
    
}

#Main.java

/*
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 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */
package com.gokisoft.lesson06.bt995;

import java.util.Scanner;

/**
 *
 * @author diepvan
 */
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        
        System.out.println("Nhap so HCN can them: ");
        int N = Integer.parseInt(scan.nextLine());
        
        HinhChuNhat[] hcnList = new HinhChuNhat[N];
        for (int i = 0; i < N; i++) {
            double cd, cr;
            System.out.println("Nhap chieu dai: ");
            cd = Double.parseDouble(scan.nextLine());
            System.out.println("Nhap chieu rong: ");
            cr = Double.parseDouble(scan.nextLine());
            
            hcnList[i] = new HinhChuNhat();
            
            hcnList[i].setDaiRong(cd, cr);
        }
        
        System.out.println("Thong tin HCN: ");
        for (HinhChuNhat hcn : hcnList) {
            System.out.println("Chieu dai: " + hcn.getChieuDai() + ", chieu rong: " + 
                    hcn.getChieuRong() + "Dien tich: " + hcn.dientichHCN());
        }
        
        double max = hcnList[0].dientichHCN();
        int index = 0;
        
        for (int i = 1; i < N; i++) {
            if(hcnList[i].dientichHCN() > max) {
                max = hcnList[i].dientichHCN();
                index = i;
            }
        }
        
        HinhChuNhat hcn = hcnList[index];
        System.out.println("Thong tin HCN co dien tich MAX");
        System.out.println("Chieu dai: " + hcn.getChieuDai() + ", chieu rong: " + 
                    hcn.getChieuRong() + "Dien tich: " + hcn.dientichHCN());
    }
}