Map集合遍历总结

Map<String,Integer> scores = new HashMap<String,Integer>();
        scores.put("Jim", 100);
        scores.put("Kate", 10);
        //第一种
        Set<String> names = scores.keySet();//获取集合中所有key-value的key组成的Set集合"Jim"   "Kate"
        //加强循环
        for (String key : names) {
            int value = scores.get(key);
            System.out.println(value);
        }
        //迭代器
        Iterator<String> iterator = names.iterator();
        while(iterator.hasNext()) {
            String key = iterator.next();
            int value = scores.get(key);
            System.out.println(value);
        }
        //第二种
        Set<Map.Entry<String, Integer>> entries =  scores.entrySet();//将HashMap集合中key-value用Entry对象包含 Set<Map.Entry<K, V>> entrySet();
        //加强循环
        for (Map.Entry<String, Integer> entry : entries) {
            String key = entry.getKey();
            int value = entry.getValue();
            System.out.println(value);
        }
        //迭代器
        Iterator<Map.Entry<String, Integer>> it = entries.iterator();// Iterator<E> iterator();
        while(it.hasNext()) {
            Map.Entry<String, Integer> entry = it.next();
            String key = entry.getKey();
            int value = entry.getValue();
            System.out.println(value);
        }