HashMap 键是Student值 是String 的案例
键是Student， 如果不重写，则键肯定不一致， 所以需要重写键对象的hashcode() equals()
LinkedHashMap 底层是链表，怎么存怎么取
TreeMap
键如果是自定义对象，则该对象必须有比较的功能
public class demon7_hashmapHashMap {
/*
* 嵌套HashMap
* 键是学生 值是学生归属地
* 有多个班级 键是班级 值是班级号
*/
public static void main(String[] args) {
HashMap<Student, String> hm1 = new HashMap<>();
hm1.put(new Student("张三",23), "北京");
hm1.put(new Student("李四",24), "北京");
hm1.put(new Student("王五",25), "上海");
hm1.put(new Student("赵柳",26), "广州");
//System.out.println(hm1);
HashMap<Student, String> hm2 = new HashMap<>();
hm2.put(new Student("唐僧",1023), "北京");
hm2.put(new Student("悟空",1024), "北京");
hm2.put(new Student("八戒",1025), "上海");
hm2.put(new Student("沙僧",926), "广州");
//System.out.println(hm2);
HashMap<HashMap<Student, String>, Integer> grade = new HashMap<>();
grade.put(hm1, 88);
grade.put(hm2, 89);
for (HashMap<Student, String> hm : grade.keySet()) {
Integer value = grade.get(hm);
for (Student s : hm.keySet()) {
String addr = hm.get(s);
System.out.println(s + "..." + addr + "..." + value);
}
}
}
}
public class test1 {
/*
* 需求：统计字符串中每个字符出现的次数
*/
public static void main(String[] args) {
String str = "aaaabbbcccccccccc";
char[] arr = str.toCharArray();
HashMap<Character,Integer> hm = new HashMap<>();
for (char c : arr) {
/*if (!hm.containsKey(c)){
hm.put(c, 1);
}else {
hm.put(c, hm.get(c)+1);
}*/
hm.put(c, !hm.containsKey(c)? 1 : hm.get(c)+1 );
}
for (Character key : hm.keySet()) {
System.out.println(key + " = " + hm.get(key));
}
System.out.println(hm.get(‘a‘));
}
}
public class test2_dizhu2 {
public static void main(String[] args) {
String[] num = {"3","4","5","6","7","8","9","10","J","Q","K","A","2"};
String[] color = {"红","黑","梅","花"};
HashMap<Integer, String> hm = new HashMap<>(); //存贮索引和牌
ArrayList<Integer> list = new ArrayList<>(); // 存索引
int index= 0 ;
for (String s1 : color) {
for (String s2 : num) {
hm.put(index, s1.concat(s2));
list.add(index);
index++;
}
}
hm.put(index, "小王");
list.add(index);
index++;
hm.put(index, "大王");
list.add(index);
Collections.shuffle(list); //随机打乱顺序，相当于洗牌
TreeSet<Integer> gaojin = new TreeSet<>();
TreeSet<Integer> longwu = new TreeSet<>();
TreeSet<Integer> me = new TreeSet<>();
TreeSet<Integer> dipai= new TreeSet<>();
for (int i = 0; i < list.size(); i++) { //发牌 存 牌的索引
if (i>=list.size()-3) {
dipai.add(list.get(i));
} else if (i%3==0) {
gaojin.add(list.get(i));
}else if (i%3==1) {
longwu.add(list.get(i));
}else {
me.add(list.get(i));
}
}
lookPoker(hm, gaojin, "高进");
lookPoker(hm, longwu, "龙武");
lookPoker(hm, me, "xxx");
lookPoker(hm, dipai, "底牌");
}
//看牌的参数列表： hashMap
public static void lookPoker(HashMap<Integer, String> hm, TreeSet<Integer> ts, String name) {
System.out.print(name + "的牌是：");
for (Integer i : ts) { // ts代表双列集合的键的集合
System.out.print(hm.get(i)+ " ");
}
System.out.println();
}
}
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.TreeSet;
public class test3 {
/**
* * A:案例演示
* 模拟斗地主洗牌和发牌并对牌进行排序的代码实现
*
* 分析:
* 1,买一副扑克,其实就是自己创建一个集合对象,将扑克牌存储进去
* 2,洗牌
* 3,发牌
* 4,看牌
*/
public static void main(String[] args) {
//1,买一副扑克,其实就是自己创建一个集合对象,将扑克牌存储进去
String[] num = {"3","4","5","6","7","8","9","10","J","Q","K","A","2"};
String[] color = {"红桃","黑桃","方片","梅花"};
HashMap<Integer, String> hm = new HashMap<>(); //存储索引和扑克牌
ArrayList<Integer> list = new ArrayList<>(); //存储索引
int index = 0;
//拼接扑克牌并索引和扑克牌存储在hm中
for(String s1 : num) { //获取数字
for(String s2 : color) { //获取颜色
hm.put(index, s2.concat(s1));
list.add(index); //将索引0到51添加到list集合中
index++;
}
}
//将小王添加到双列集合中
hm.put(index, "小王");
list.add(index); //将52索引添加到集合中
index++;
hm.put(index, "大王");
list.add(index); //将53索引添加到集合中
//2,洗牌
Collections.shuffle(list);
//3,发牌
TreeSet<Integer> gaojin = new TreeSet<>();
TreeSet<Integer> longwu = new TreeSet<>();
TreeSet<Integer> me = new TreeSet<>();
TreeSet<Integer> dipai = new TreeSet<>();
for(int i = 0; i < list.size(); i++) {
if(i >= list.size() - 3) {
dipai.add(list.get(i)); //将三张底牌存储在底牌集合中
}else if(i % 3 == 0) {
gaojin.add(list.get(i));
}else if(i % 3 == 1) {
longwu.add(list.get(i));
}else {
me.add(list.get(i));
}
}
//看牌
lookPoker(hm, gaojin, "高进");
lookPoker(hm, longwu, "龙五");
lookPoker(hm, me, "xxx");
lookPoker(hm, dipai, "底牌");
}
/*
* 看牌
* 1,返回值类型void
* 2,参数列表HashMap,TreeSet,String name
*/
public static void lookPoker(HashMap<Integer, String> hm,TreeSet<Integer> ts ,String name) {
System.out.print(name + "的牌是:");
for(Integer i : ts) { //i代表双列集合中的每一个键
System.out.print(hm.get(i) + " ");
}
System.out.println();
}
}
原文地址：https://www.cnblogs.com/yaobiluo/p/11306352.html
时间： 2024-10-09 21:56:55