Map的merge()用法

1、java8 Map的新用法

 Job job = new Job("李四","語文",98);
        Job job1 = new Job("李四","數學",85);
        Job job2 = new Job("王五","語文",90);
        Job job3 = new Job("王五","數學",84);
        Job job4 = new Job("趙三","語文",89);
        Job job5 = new Job("趙三","數學",82);
        List<Job> list = new ArrayList<>();
        list.add(job);
        list.add(job1);
        list.add(job2);
        list.add(job3);
        list.add(job4);
        list.add(job5);
        Map<String,Integer>  treeMap = new HashMap<>();
        list.forEach( jobs -> {
            treeMap.merge(jobs.getName(),jobs.getScore(),Integer::sum);
        });
        System.out.println("觸發信息內容："+ com.alibaba.fastjson.JSON.toJSONString(treeMap));

結果：

觸發信息內容：{"李四":183,"趙三":171,"王五":174}

 結論：可以較好的處理統計