5.第五题（Map）设计Account 对象如下：
private long id; private double balance; private String password;
要求完善设计，使得该Account 对象能够自动分配id。 给定一个List 如下：
List list = new ArrayList(); list.add(new Account(10.00, “1234”)); list.add(new Account(15.00, “5678”)); list.add(new Account(0, “1010”));
要求把List 中的内容放到一个Map 中，该Map 的键为id，值为相应的Account 对象。 最后遍历这个Map，打印所有Account 对象的id 和余额。
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package com.company; import java.util.UUID; /** * Created by ttc on 2018/1/11. */ public class Account { private String sid;//使用UUID来生成 private double balance; private String password; public Account(double balance, String password) { this.balance = balance; this.password = password; //自动分配账号 this.sid = UUID.randomUUID().toString(); } public String getSid() { return sid; } public void setSid(String sid) { this.sid = sid; } public double getBalance() { return balance; } public void setBalance(double balance) { this.balance = balance; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
package com.company; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * Created by ttc on 2018/1/11. */ public class TestAccount { public static void main(String[] args) { List<Account> accountList = new ArrayList<>(); accountList.add(new Account(100,"123")); accountList.add(new Account(10,"456")); accountList.add(new Account(80,"111")); //将数据转移到map结构 Map<String,Account> accountMap = new HashMap<String,Account>(); for(Account account : accountList) { accountMap.put(account.getSid(),account); } for(Map.Entry<String,Account> entry: accountMap.entrySet()) { System.out.println(entry.getKey() + " " + entry.getValue().getSid()); } } }
Account的id自增长版本
package com.company; import java.util.UUID; /** * Created by ttc on 2018/1/11. */ public class Account { // private String sid;//使用UUID来生成 private long sid; private double balance; private String password; private static int object_count = 0; public Account(double balance, String password) { this.balance = balance; this.password = password; //自动分配账号 //this.sid = UUID.randomUUID().toString(); //先获得当前本类已经创建了多少个对象 this.sid = Account.object_count + 1; Account.object_count++; } public long getSid() { return sid; } public void setSid(long sid) { this.sid = sid; } public double getBalance() { return balance; } public void setBalance(double balance) { this.balance = balance; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
public static void main(String[] args) { List<Account> accountList = new ArrayList<>(); accountList.add(new Account(100,"123"));//A accountList.add(new Account(10,"456"));//B accountList.add(new Account(80,"111")); accountList.add(new Account(330,"333")); //将数据转移到map结构 Map<Long,Account> accountMap = new HashMap<Long,Account>(); for(Account account : accountList) { accountMap.put(account.getSid(),account); } for(Map.Entry<Long,Account> entry: accountMap.entrySet()) { System.out.println(entry.getKey() + " " + entry.getValue().getSid()); } }
6.第六题（List）已知有一个Worker 类如下：
public class Worker { private int age; private String name; private double salary; public Worker (){} public Worker (String name, int age, double salary) { this.name = name; this.age = age; this.salary = salary; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public double getSalary(){ return salary; } public void setSalary(double salary){ this.salary = salary; } public void work(){ System.out.println(name + “ work”); } }
完成下面的要求
- 创建一个List，在List 中增加三个工人，基本信息如下：
姓名 年龄 工资
zhang3 18 3000
li4 25 3500
wang5 22 3200
- 在li4 之前插入一个工人，信息为：姓名：zhao6，年龄：24，工资3300
- 删除wang5 的信息
- 利用for 循环遍历，打印List 中所有工人的信息
- 利用迭代遍历，对List 中所有的工人调用work 方法。
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List<Worker> workerList = new ArrayList<>(); workerList.add(new Worker("zhangsan",12,2445)); workerList.add(new Worker("lisi",32,5445)); workerList.add(new Worker("wangwu",22,7445)); Worker worker = new Worker("zhaoliu",33,5645); workerList.add(1,worker); workerList.remove(3); for(int i = 0; i < workerList.size();i++) { System.out.println(workerList.get(i)); } for(Worker worker1 : workerList){ worker1.work(); }
经典练习
一篇英文文章，单词间用空格分割，统计出现了哪些单词，以及每个单词出现的次数。
public static void main(String[] args) { //问题结果 // this----------2 // is------------2 // a-------------2 // book----------1 // that----------1 // desk----------1 String article = "this this is a book that is a desk";//问题的开始，问题的输入 String[] words = article.split(" "); //Map<String,Integer> key保存的是单词，value保存的是该单词出现的次数 Map<String,Integer> map = new HashMap<>(); //this----2 //考察单词数组中的每一个单词, for(int i = 0; i < words.length; i++) { //考察每一个单词， if(map.containsKey(words[i]))//如果map的key中存在该单词,将该单词出现的次数加1 { int count = map.get(words[i]); count++; map.put(words[i],count); } else//如果map的key中不存在该单词，将该单词添加到map中 { map.put(words[i],1); } } for(String word : map.keySet()) { System.out.println(word+"--------"+map.get(word)); } }
Set
和LIst类似，主要区别是不能保存重复元素
生成100000个UUID，判断是否有重复的？
Set<String> stringSetUUID = new HashSet<>(); for(int i = 0; i < 10000000; i++) { UUID uuid = UUID.randomUUID(); stringSetUUID.add(uuid.toString()); } System.out.println(stringSetUUID.size());
扑克模拟问题续
随机发出5张牌，判断牌型
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package com.company; /** * Created by ttc on 2017/12/28. */ public class Card { private int value;//牌值 private String color;//花色 public Card(int value, String color) { this.value = value; this.color = color; } public int getValue() { return value; } public void setValue(int value) { this.value = value; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public String toString() { String str = ""; if(value == 11) { str = "J"; } else if(value == 12) { str = "Q"; } else if(value == 13) { str = "K"; } else if(value == 1) { str = "A"; } else { str = value+""; } return color+str; } }
package com.company; import java.util.*; /** * Created by ttc on 2017/12/28. */ public class Poker { List<Card> cards = new ArrayList<Card>(); private String[] colors = {"红桃", "方片", "黑桃","草花"}; private int[] values = {1,2,3,4,5,6,7,8,9,10,11,12,13}; public Poker() { //初始化，创建52张扑克牌 //红桃13张 1，2，3... //方片13张 //外层循环生成花色 //里层循环生成牌值 for(int i = 0; i < colors.length; i++) { for(int j = 0; j < values.length; j++) { Card card = new Card(values[j],colors[i]); // card.setColor(colors[i]); // card.setValue(values[j]); cards.add(card); } } } //洗牌方法 public void shuffle() { Collections.shuffle(cards); } //打印扑克中的每一张牌 public void output() { System.out.println(cards); } //发一手牌 public List<Card> takeHands() { List<Card> cardList = new ArrayList<>(); //把cards的前5张牌放到cardList里 int count = 0; for(Card card : cards) { cardList.add(card); count++; if(count == 5) { break; } } return cardList; } //判断牌型 public String judgeType(List<Card> cardList) { boolean isSameColor = false;//是否同花 boolean isShunZi = false;//是否顺子 String strType = ""; Set<String> setColors = new HashSet<>(); for(Card card : cardList) { setColors.add(card.getColor()); } if(setColors.size() == 1) { isSameColor = true; // System.out.println("同花"); } //5张牌，排好序，（最后一张减去第一张 == 4 && 把5张牌放到set中，set.size（）== 5） Set<Integer> setValues = new HashSet<>(); List<Integer> listValues = new ArrayList<>(); for(Card card : cardList) { int value = card.getValue(); setValues.add(value); listValues.add(value); } Collections.sort(listValues); int between = listValues.get(4) - listValues.get(0); if(between == 4 && setValues.size() == 5) { isShunZi = true; // System.out.println("顺子"); } if(isSameColor == true && isShunZi == true) { strType = "同花顺"; // System.out.println("同花顺"); } else if(isSameColor == true) { strType = "同花"; // System.out.println("同花"); } else if(isShunZi == true) { strType = "顺子"; // System.out.println("顺子"); } else if(setValues.size() == 5) { strType = "杂牌"; // System.out.println("杂牌"); } else if(setValues.size() == 4) { strType = "一对"; // System.out.println("一对"); } else if(setValues.size() == 3) { // System.out.println("两对或3条"); // System.out.println("四带一或三带二"); Map<Integer, Integer> mapCardValue2Counts = new HashMap<>(); //将5张牌从list结构转化到map中 for(Card card: cardList) { //map的key中是否包含当前牌的值，如果包含,拿出当前牌值已经出现的次数 if(mapCardValue2Counts.containsKey(card.getValue())) { int count = mapCardValue2Counts.get(card.getValue()); count++; mapCardValue2Counts.put(card.getValue(),count); } else//不包含 { mapCardValue2Counts.put(card.getValue(),1); } } // (9,3),(5,1),(3,1) // (13,2),(5,2),(2,1) for(Map.Entry<Integer, Integer> entry : mapCardValue2Counts.entrySet()) { if(entry.getValue() == 3) { strType = "三带一"; // System.out.println("三带一"); break; } else if(entry.getValue() == 2) { strType = "两对"; // System.out.println("两对"); break; } } } else if(setValues.size() == 2) { // System.out.println("四带一或三带二"); Map<Integer, Integer> mapCardValue2Counts = new HashMap<>(); //将5张牌从list结构转化到map中 for(Card card: cardList) { //map的key中是否包含当前牌的值，如果包含,拿出当前牌值已经出现的次数 if(mapCardValue2Counts.containsKey(card.getValue())) { int count = mapCardValue2Counts.get(card.getValue()); count++; mapCardValue2Counts.put(card.getValue(),count); } else//不包含 { mapCardValue2Counts.put(card.getValue(),1); } } // (4,4),(9,1) // (3,3),(10,2) for(Map.Entry<Integer, Integer> entry : mapCardValue2Counts.entrySet()) { if(entry.getValue() == 4) { strType = "四带一"; // System.out.println("四带一"); break; } else if(entry.getValue() == 3) { strType = "三带二"; // System.out.println("三带二"); break; } } } return strType; } }
package com.company; import java.util.ArrayList; import java.util.List; public class Main { public static void main(String[] args) { // write your code here Poker poker = new Poker(); poker.output(); // poker.shuffle();//洗牌 System.out.println(); poker.output(); // List<Card> cardList = poker.takeHands(); List<Card> cardList = new ArrayList<>(); Card card = new Card(5,"黑桃"); cardList.add(card); card = new Card(5,"红桃"); cardList.add(card); card = new Card(9,"草花"); cardList.add(card); card = new Card(8,"草花"); cardList.add(card); card = new Card(8,"方片"); cardList.add(card); System.out.println(cardList); String type = poker.judgeType(cardList); System.out.println(type); } }
