将map中value和key互转,将多个key组合成字符串输出

    public static void main(String[] args) {
        Map map = new HashMap();
        map.put("aa", 1);
        map.put("bb", 2);
        map.put("cc", 1);

        Map values = new HashMap();
        List list = new ArrayList();
        Iterator iterator = map.keySet().iterator();
        while (iterator.hasNext()) {
            Object key = iterator.next();
            Object value = map.get(key);
            if (map.containsValue(value)) {
                if (values.containsKey(value)) {
                    list = (List) values.get(value);
                } else {
                    list = new ArrayList();
                }
                list.add(key);
                values.put(value, list);
            }
        }

        System.out.println("result-----------------------");
        iterator = values.keySet().iterator();
        while (iterator.hasNext()) {
            Object value = iterator.next();
            List result = (List) values.get(value);
            if (result.size() > 1) {
                System.out.println("value :" + value + "  -> keys:" + result.toString());
            }
        }
    }

运行结果

result-----------------------
value :1  -> keys:[aa, cc]

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