【Java】Collection的其他知识-开发者社区

文章目录

前言
内容概览
更新记录
可变参数
Collection常用的静态方法
综合案例
总结

前言

1.之前学过，因此本文是个人复习笔记，为视频的总结以及个人思考，可能不是很详细。

2.教程是b站黑马程序员的JAVASE基础课程，笔记中的大部分图片来自于视频中的PPT截图。

3.Java环境为Java SE 17.0.3.1，IntelliJ IDEA版本为2025.2

https://www.bilibili.com/video/BV1Cv411372m

内容概览

1.本文内容主要包括可变参数，Collection的一些api，以及一个综合案例的实现

2.笔记对应视频142~144节

更新记录

无

可变参数

一种特殊形参，定义在方法、构造器的形参列表，可以不传数据，或传单个或多个数据，或传数组

数据类型…参数名称

注意事项：

可变参数本质是一个数组；一个形参列表中可变参数只有有一个，并放在最后

Sets5.java

package com.zbhgis.sets; import java.util.Arrays; public class Sets5 { public static void main(String[] args) { test(); test(1); test(1, 2, 3); test(new int[]{1, 2, 3, 4}); } private static void test(int... num) { System.out.println(num.length); System.out.println(Arrays.toString(num)); } }

打印结果

0 [] 1 [1] 3 [1, 2, 3] 4 [1, 2, 3, 4]

Collection常用的静态方法

Sets6.java

package com.zbhgis.sets; import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Sets6 { public static void main(String[] args) { List<Integer> list = new ArrayList<>(); Collections.addAll(list, 7, 4, 1, 8, 5, 2); System.out.println(list); Collections.shuffle(list); System.out.println(list); Collections.shuffle(list); System.out.println(list); Collections.sort(list); System.out.println(list); } }

打印结果

[7, 4, 1, 8, 5, 2] [4, 2, 8, 7, 1, 5] [7, 5, 4, 8, 2, 1] [1, 2, 4, 5, 7, 8]

综合案例

斗地主案例的实现

Card.java

package com.zbhgis.sets; public class Card { private String number; private String color; private int size; public Card() { } public Card(String number, String color, int size) { this.number = number; this.color = color; this.size = size; } @Override public String toString() { return color + number; } public String getNumber() { return number; } public void setNumber(String number) { this.number = number; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public int getSize() { return size; } public void setSize(int size) { this.size = size; } }

Room.java

package com.zbhgis.sets; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class Room { private List<Card> allCards = new ArrayList<>(); public Room() { String[] numbers = {"3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A", "2"}; String[] colors = {"♠", "♥", "♣", "♦"}; int size = 0; for (String number : numbers) { size++; for (String color : colors) { Card c = new Card(number, color, size); allCards.add(c); } } Card c1 = new Card("", "S", ++size); Card c2 = new Card("", "B", ++size); Collections.addAll(allCards, c1, c2); System.out.println("新牌：" + allCards); } public void start() { // 洗牌 Collections.shuffle(allCards); System.out.println("洗牌后：" + allCards); List<Card> P1 = new ArrayList<>(); List<Card> P2 = new ArrayList<>(); List<Card> P3 = new ArrayList<>(); // 发牌 for (int i = 0; i < allCards.size() - 3; ) { Card c1 = allCards.get(i++); P1.add(c1); Card c2 = allCards.get(i++); P2.add(c2); Card c3 = allCards.get(i++); P3.add(c3); } // 给玩家的牌排序 sortCard(P1); sortCard(P2); sortCard(P3); // 看牌 System.out.println("P1" + P1); System.out.println("P2" + P2); System.out.println("P3" + P3); // 最后三张牌 List<Card> lastThreeCards = allCards.subList(allCards.size() - 3, allCards.size()); System.out.println("底牌：" + lastThreeCards); // 抢地主 P1.addAll(lastThreeCards); sortCard(P1); System.out.println("P1新牌：" + P1); } private void sortCard(List<Card> cards) { Collections.sort(cards, new Comparator<Card>() { @Override public int compare(Card o1, Card o2) { return o2.getSize() - o1.getSize(); } }); } }

GameDemo.java

package com.zbhgis.sets; public class GameDemo { public static void main(String[] args) { Room m = new Room(); m.start(); } }

打印结果

新牌：[♠3, ♥3, ♣3, ♦3, ♠4, ♥4, ♣4, ♦4, ♠5, ♥5, ♣5, ♦5, ♠6, ♥6, ♣6, ♦6, ♠7, ♥7, ♣7, ♦7, ♠8, ♥8, ♣8, ♦8, ♠9, ♥9, ♣9, ♦9, ♠10, ♥10, ♣10, ♦10, ♠J, ♥J, ♣J, ♦J, ♠Q, ♥Q, ♣Q, ♦Q, ♠K, ♥K, ♣K, ♦K, ♠A, ♥A, ♣A, ♦A, ♠2, ♥2, ♣2, ♦2, S, B] 洗牌后：[♥5, ♣K, ♥J, ♣4, B, ♣5, ♣6, ♠10, ♥3, ♣3, S, ♦8, ♦6, ♥10, ♥A, ♣A, ♦J, ♥K, ♠8, ♥2, ♦7, ♥8, ♦K, ♣Q, ♦4, ♣J, ♠J, ♦Q, ♣7, ♠5, ♠4, ♦9, ♠3, ♣8, ♦5, ♣10, ♣9, ♠2, ♠7, ♥Q, ♦3, ♠6, ♠A, ♦10, ♥9, ♦A, ♦2, ♥7, ♥4, ♠K, ♣2, ♠9, ♠Q, ♥6] P1[♣A, ♠A, ♦A, ♦Q, ♥Q, ♣9, ♠8, ♥8, ♣8, ♣6, ♦6, ♥5, ♣4, ♦4, ♠4, ♥4, ♣3] P2[B, S, ♥2, ♠2, ♦2, ♣K, ♦K, ♠K, ♦J, ♣J, ♠10, ♥10, ♦10, ♦9, ♣7, ♦5, ♦3] P3[♣2, ♥A, ♥K, ♣Q, ♥J, ♠J, ♣10, ♥9, ♦8, ♦7, ♠7, ♥7, ♠6, ♣5, ♠5, ♥3, ♠3] 底牌：[♠9, ♠Q, ♥6] P1新牌：[♣A, ♠A, ♦A, ♦Q, ♥Q, ♠Q, ♣9, ♠9, ♠8, ♥8, ♣8, ♣6, ♦6, ♥6, ♥5, ♣4, ♦4, ♠4, ♥4, ♣3]