给定10万数据，数据范围[0~1000）,统计出现次数最多的10个数据，并打印出现次数

采用集合实现：

import java.util.*;
public class MapDemo {
    public static void main(String[] args) {
        Random random = new Random();
        int[] arr = new int[10];//存储出现数字前十的个数
        HashMap<Integer, Integer> hashMap = new HashMap<>();//统计各个数字出现的次数
        ArrayList<Integer> arrayList = new ArrayList<>();
        //统计每个数字出现的次数
        for (int i = 0; i < 100000; i++) {
            int num = random.nextInt(1000);
            if(hashMap.containsKey(num)){
                hashMap.put(num,hashMap.get(num)+1);
            }else {
                hashMap.put(num,1);
            }
        }
        for (Integer key:hashMap.keySet()
             ) {
            arrayList.add(hashMap.get(key));
        }

        Comparator<Integer> comparator = new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o2-o1;
            }

            @Override
            public boolean equals(Object obj) {
                return false;
            }
        };
        Collections.sort(arrayList,comparator);
        for (int i = 0; i < 10; i++) {
            arr[i] = arrayList.get(i);
        }
        System.out.println("次数前十："+Arrays.toString(arr));
        System.out.println("出现数字前十：");
        for (int i = 0; i < arr.length; i++) {
            for (Integer key:hashMap.keySet()) {
                if(arr[i] == hashMap.get(key)){
                    System.out.println("数字："+key+" "+"出现次数："+hashMap.get(key));
                }
            }
        }

    }

}

某次结果如图：