初识HashMap

HashMap：无序，不重复，无索引

HashMap小练习：

import java.text.ParseException;
import java.util.*;
import java.util.function.BiConsumer;
import java.util.function.Consumer;import static java.lang.Math.abs;public class Test3 {public  static void main(String[] args) {//定义数组，存储4个景点String[] arr={"A","B","C","D"};ArrayList<String> list=new ArrayList<>();Random r=new Random();for (int i = 0; i < 80; i++) {int i1 = r.nextInt(arr.length);list.add(arr[i1]);}HashMap<String,Integer> hashMap=new HashMap<>();for (String name : list) {//判断当前投票的景点是否存在if(hashMap.containsKey(name)){//存在int count = hashMap.get(name);count++;hashMap.put(name,count);}else {//不存在hashMap.put(name,1);}}//求最大值int max=0;Set<Map.Entry<String, Integer>> entries = hashMap.entrySet();//判断哪个景点的次数跟最大值一样，如果一样，打印出来for (Map.Entry<String, Integer> entry : entries) {int count = entry.getValue();if(count>max){max=count;}}System.out.println(max);}}