public class MyArrayList<E> { 
   private E[] array; 
   private int size;
    ... 
    }

// 定義了一個元素是 Book類 引用的 MyArrayList 
MyArrayList<Book> books = new MyArrayList<Book>(); 
books.add(new Book()); 

// 會產(chǎn)生編譯錯誤，Person 類型無法轉(zhuǎn)換為 Book 類型 
books.add(new Person()); 

// 不需要做類型轉(zhuǎn)換 
Book book = book.get(0); 

// 會產(chǎn)生編譯錯誤，Book 類型無法轉(zhuǎn)換為 Person 類型 
Person person = book.get(0);

import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;
public class ListDemo {
    public static void main(String[] args) {
        List<String> courses = new ArrayList<>();
        courses.add("Kobe");
        courses.add("Jordan");
        courses.add("Westbrook");
        courses.add("Durant");

        // 和數(shù)組一樣，允許添加重復(fù)元素
        courses.add("Kobe");

        // 按照添加順序打印
        System.out.println(courses);

        // 類似數(shù)組下標(biāo)的方式訪問
        System.out.println(courses.get(0));

        //給目標(biāo)位置設(shè)置新元素
        courses.set(0, "Jordan");
        System.out.println(courses);

        // 截取部分 [1, 3) 注意這里是左開右閉區(qū)區(qū)間
        List<String> subCourses = courses.subList(1, 3);
        System.out.println(subCourses);

        // 重新構(gòu)造
        List<String> courses2 = new ArrayList<>(courses);
        System.out.println(courses2);
        List<String> courses3 = new LinkedList<>(courses);
        System.out.println(courses3);

        // 引用的轉(zhuǎn)換
        ArrayList<String> courses4 = (ArrayList<String>)courses2;
        System.out.println(courses4);
        //LinkedList<String> c = (LinkedList<String>)course2; 錯誤的類型
        LinkedList<String> courses5 = (LinkedList<String>)courses3;
        System.out.println(courses5);
        //ArrayList<String> c = (ArrayList<String>)course3; 錯誤的類型

        }
    }

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

public class TestDemo {
    public static void main(String[] args) {
        List<Card> deck = CardDemo.buyDeck();
        System.out.println("買來的新牌");
        System.out.println(deck);

        System.out.println("===========================");
        CardDemo.shuffle(deck);
        System.out.println("洗過后的牌");
        System.out.println(deck);
        System.out.println("===========================");

        //三個人，每個人輪流抓牌，一個人五張牌
        List<List<Card>> hands = new ArrayList<>();//二維數(shù)組的思維
        hands.add(new ArrayList<>());//加一個人
        hands.add(new ArrayList<>());//再加一個人
        hands.add(new ArrayList<>());//再加一個人，共三個人

        for (int i = 0; i < 5 ; i++){
            for (int j = 0; j < 3; j++){
                hands.get(j).add(deck.remove(0));
                //這里的remove返回順序表里被移除的元素，剛好牌堆里少一張牌
            }
        }

        System.out.println("剩余的牌");
        System.out.println(deck);
        System.out.println("A手中的牌");
        System.out.println(hands.get(0));
        System.out.println("B手中的牌");
        System.out.println(hands.get(1));
        System.out.println("C手中的牌");
        System.out.println(hands.get(2));

    }
}

public class Card {
    private int rank;//牌值
    private String suit;//花色

    public Card(int rank, String suit) {
        this.rank = rank;
        this.suit = suit;
    }

    @Override
    public String toString() {
        return String.format("[%s %d]", suit, rank);
    }
}

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

public class CardDemo {
    private static final String[] suits = {"?", "?", "?", "?"};

    //買一副牌
    public static List<Card> buyDeck() {
        List<Card> deck = new ArrayList<>(52);
        for (int i = 0; i < 4; i++) {
            for (int j = 1; j <= 13; j++) {
                String suit = suits[i];
                int rank = j;
                deck.add(new Card(rank, suit));//順序表默認(rèn)是尾插
            }
        }
        return deck;
    }

    public static void swap(List<Card> deck, int i, int j) {
        Card temp = deck.get(i);
        deck.set(i, deck.get(j));
        deck.set(j, temp);
    }

    public static void shuffle(List<Card> deck){
        Random rand = new Random(20211122);
        for (int i = deck.size() - 1; i > 0; i--){
            int r = rand.nextInt(i);//生成0~i的隨機正整數(shù)
            swap(deck, i ,r);
        }
    }