关于HashMap相同key累加value的问题

import java.util.HashMap;
import java.util.Map;
public class Test {
	public static void main(String[] args) {
		Map<String, Long> map = new HashMap<String, Long>();
		map.put("k", 1L);
		map.put("k", 2L);
		map.put("k", 3L);
		System.out.println(map);
	}
}

#!/usr/bin/perl
use strict;
use Data::Dumper;
my %map;
$map{"k"}+=1;
$map{"k"}+=2;
$map{"k"}+=3;
print Dumper(\%map);

List<Map<String, List<RecommendationListBO>>> hashList = new ArrayList<>();
Iterator<Map.Entry<String, List<RecommendationListBO>>> iterator = recommendationHashMap.entrySet().iterator();
Map.Entry<String, List<RecommendationListBO>> entry;
while (iterator.hasNext()) {
    entry = iterator.next();
    // 往newMap中放入新的Entry
    HashMap<String, List<RecommendationListBO>> newMap = new LinkedHashMap<>();
    newMap.put(entry.getKey().split(",")[0], entry.getValue());
    hashList.add(newMap);
}