将两个Map< String，String>相加的最佳方法是什么? [英] What's the best way to sum two Map<String,String>?

问题描述

我有以下地图.

Map<String,String> map1= new HashMap<String, String>(){{
       put("no1","123"); put("no2","5434"); put("no5","234");}};

Map<String,String> map1 = new HashMap<String, String>(){{
       put("no1","523"); put("no2","234"); put("no3","234");}};

sum(map1, map2);

我想将它们合并为一个，将相似的键值汇总在一起.使用Java 7或番石榴库能做到的最好方法是什么?

I want to join them to one, summing up similar keyed values together. What;s the best way I could do it using java 7 or guava libraries ?

预期输出

Map<String, String> output = { { "no1" ,"646"}, { "no2", "5668"}, {"no5","234"}, {"no3","234" }  }

推荐答案

private static Map<String, String> sum(Map<String, String> map1, Map<String, String> map2) {
        Map<String, String> result = new HashMap<String, String>();
        result.putAll(map1);
        for (String key : map2.keySet()) {
            String value = result.get(key);
            if (value != null) {
                Integer newValue = Integer.valueOf(value) + Integer.valueOf(map2.get(key));
                result.put(key, newValue.toString());
            } else {
                result.put(key, map2.get(key));
            }
        }
        return result;
    }

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