Java basic- OOP - căn bản - Tổng hợp ví dụ lập trính hướng đổi tượng trong java - mới bắt đầu với OOP

#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.lesson03;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

/**
 *
 * @author diepvan
 */
public class Main {
    static ArrayList<Product> products = new ArrayList<>();
    static Scanner scan = new Scanner(System.in);
    
    public static void main(String[] args) {
        int choose;
        
        do {
            showMenu();
            choose = Integer.parseInt(scan.nextLine());
            
            switch (choose) {
                case 1:
                    input();
                    break;
                case 2:
                    display();
                    break;
                case 3:
                    sort();
                    break;
                case 4:
                    System.out.println("Thoat!!!");
                    break;
                default:
                    System.out.println("Nhap sai!!!");
            }
        } while(choose != 4);
    }
    
    static void showMenu() {
        System.out.println("1. Nhap N san pham");
        System.out.println("2. Hien thi thong tin");
        System.out.println("3. Sap xep theo gia & hien thi");
        System.out.println("4. Thoat");
        System.out.println("Chon: ");
    }

    private static void input() {
        System.out.println("Nhap so san pham can them: ");
        int n = Integer.parseInt(scan.nextLine());
        
//        Product p = new Product(); Cach 2
        Product p; //Cach 3
        for (int i = 0; i < n; i++) {
//            Product p = new Product(); -> cach 1
            p = new Product();
            p.input();
            
            products.add(p);
        }
//        Product p = new Product();
//        p.name = "A";
//        p.display();
//        Product p3 = p;
//        
//        Product p2 = new Product();
//        p2.display();
//        
//        p = new Product();
//        p.name = "C";
//        p.display();
//        
//        System.out.println(p.name + ", " + p3.name);
    }

    private static void display() {
        System.out.println("Danh sach san pham");
        for (int i = 0; i < products.size(); i++) {
            products.get(i).display();
        }
        
        System.out.println("Danh sach san pham");
        for (Product product : products) {
            product.display();
        }
    }

    private static void sort() {
        Collections.sort(products, new Comparator<Product>() {
            @Override
            public int compare(Product o1, Product o2) {
                if(o1.price > o2.price) {
                    return 1;
                }
                return -1;
            }
        });
        
        display();
    }
}

#Product.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.lesson03;

import java.util.Scanner;

/**
 *
 * @author diepvan
 */
public class Product {
    String name;
    String manufacturerName;
    float price;

    public Product() {
    }

    public Product(String name, String manufacturerName, float price) {
        this.name = name;
        this.manufacturerName = manufacturerName;
        this.price = price;
    }
    
    public void input() {
        Scanner scan = new Scanner(System.in);
        
        System.out.println("Nhap ten: ");
        name = scan.nextLine();
        
        System.out.println("Nhap nha san xuat: ");
        manufacturerName = scan.nextLine();
        
        System.out.println("Nhap gia ban: ");
        price = Float.parseFloat(scan.nextLine());
    }
    
    public void display() {
        System.out.println("Ten = " + name + ", nha san xuat = " + manufacturerName + ", gia = " + price);
    }
}