Share Code - Tìm hiểu Collections & Generic trong Java

#Source Code Dự Án

##Class Main

/*
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package lession2;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Vector;

/**
 *
 * @author Diep.Tran
 */
public class Main {
    public static void main(String[] args) {
        //Collection
        //Phan 1 => List
        //Class Object >> List >> ArrayList
        List<Integer> list = new ArrayList<>();//Tinh chat da hinh trong lap trinh
        //Them phan tu vao trong mang
        list.add(1);
        list.add(10);
        System.out.println("=============== Turn #1");
        for (Integer v : list) {
            System.out.println(">> " + v);
        }
        list.add(1, 12);
        System.out.println("=============== Turn #2");
        for (Integer v : list) {
            System.out.println(">> " + v);
        }
        //Xoa 1 phan tu khoi mang
        list.remove(1);
        System.out.println("=============== Turn #3");
        for (Integer v : list) {
            System.out.println(">> " + v);
        }
        
        List<String> list2 = new ArrayList<>();
        list2.add("Phan tu 1");
        list2.add("Phan tu 2");
        list2.add("Phan tu 3");
        System.out.println("=============== String Turn #1");
        for (String v : list2) {
            System.out.println(">> " + v);
        }
        
        list2.remove("Phan tu 2");
        System.out.println("=============== String Turn #2");
        for (String v : list2) {
            System.out.println(">> " + v);
        }
        
        list2.clear();
        
        //duyet phan tu trong mang
        list.get(0);
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
        
        for (String string : list2) {
            System.out.println(string);
        }
        
        list2.forEach((string) -> {
            System.out.println(string);
        });
        
        //Phan 2 >> Vector
        List<Integer> list3 = new Vector<>();//Tinh chat da hinh trong lap trinh
        list3.add(123213);
        
        //Map
        Map<String, Integer> map = new HashMap<>();
        map.put("k1", 1000);
        map.put("k1", 23);
        map.put("k2", 43);
        //cach 1 => truy xuat du lieu theo key
        int v = map.get("k2");
        System.out.println(v);
        
        //Student => rollNo => duy nhat => primary key
        //StudentA => R001 => Map => R001 => StudentA
        for (Map.Entry<String, Integer> entry : map.entrySet()) {
            String key = entry.getKey();
            Integer value = entry.getValue();
            System.out.println("key = " + key);
            System.out.println("value = " + String.valueOf(value));
        }
        
//        DataMgr<Integer> dataMgr = DataMgr.getInstance();
//        dataMgr.add(12);
        
        DataMgr<People> dataMgr2 = DataMgr.getInstance();
        dataMgr2.add(new People());
        
//        DataMgr<String> dataMgr3 = DataMgr.getInstance();
//        dataMgr3.add("String");
//        
//        Object obj = dataMgr.get(0);
        
//        if(obj instanceof People) {
//            System.out.println("People");
//        } else {
//            System.out.println("Other");
//        }
    }
}

##Class People

/*
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package lession2;

/**
 *
 * @author Diep.Tran
 */
public class People {
    
}

##Class Student => Kế Thừa People

/*
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 */
package lession2;

/**
 *
 * @author Diep.Tran
 */
public class Student extends People{
    
}

##Class DataMgr => Quản lý dữ liệu

/*
 * 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 lession2;

import java.util.ArrayList;
import java.util.List;

/**
 *
 * @author Diep.Tran
 */
public class DataMgr<E extends People> {
    List<E> list = new ArrayList<>();
    
    private static DataMgr instance = null;
    
    private DataMgr() {
        
    }
    
    public synchronized static DataMgr getInstance() {
        if(instance == null) {
            instance = new DataMgr();
        }
        return instance;
    }
    
    public void add(E e) {
        list.add(e);
    }
    
    public E get(int index) {
        return list.get(index);
    }
}