java Java数组映射HashMap计算Int的出现次数

Posted 2021-05-07

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class CountOccurence
{
    public static void main(String[] args)
    {
        //Input Array
        int[] input = new int[]{1,4,5,2,3,5,1,6,4,7,1,3,6,8,2,5};

        //countMap holds the count details of each element
        Map<Integer, Integer> countMap = new HashMap<Integer, Integer>();
        for (int i = 0; i < input.length; i++)
        {
            int key = input[i];
            if (countMap.containsKey(key))
            {
                int count = countMap.get(key);
                count++;
                countMap.put(key, count);
            } else
            {
                countMap.put(key, 1);
            }
        }
        
        //Printing the Element and its occurrence in the array
        for(Entry<Integer,Integer> val : countMap.entrySet())
        {
            System.out.println(val.getKey() + " occurs " + val.getValue() + " time(s)");
        }
    }
}