Map循环遍历的常用方法

常用Map循环遍历的方法

  Map<String, Object> map = new HashMap<String, Object>();
        map.put("1", "a");
        map.put("2", "b");
        map.put("3", "c");
        System.out.println(map.containsKey("4"));

        //构造测试数据
        List<Map<String, Integer>> list = new ArrayList<>();

        HashMap<String, Integer> map1 = new HashMap<String, Integer>() {
            {
                put("a", 16);
            }
        };
        list.add(map1);
        HashMap<String, Integer> map2 = new HashMap<String, Integer>() {
            {
                put("a", 17);
            }
        };
        list.add(map2);
        HashMap<String, Integer> map3 = new HashMap<String, Integer>() {
            {
                put("a", 18);
            }
        };
        list.add(map3);

        Iterator<Map<String, Integer>> iterator = list.iterator();
        while (iterator.hasNext()) {
            Map<String, Integer> info = iterator.next();
            if (Integer.valueOf(info.get("a").toString()) > 16) {
                iterator.remove();
            }

        }
        for (Map<String, Integer> mapz : list) {
            System.out.println(mapz.get("a"));
        }

        Map<String, Object> newmap = new HashMap<>();
        newmap.put("1", "A");
        newmap.put("2", "B");
        newmap.put("3", "C");
		//方法一
        Set set = newmap.keySet();
        Iterator iterator1 = set.iterator();
        while (iterator1.hasNext()) {
            Object next = iterator1.next();
            System.out.println(next + "/" + newmap.get(next));
        }

		//方法二
        Set<Map.Entry<String, Object>> setx = newmap.entrySet();
        Iterator<Map.Entry<String, Object>> iteratorx = setx.iterator();
        while (iteratorx.hasNext()) {
            Map.Entry<String, Object> mapx = iteratorx.next();
            System.out.println(mapx.getKey() + "/" + mapx.getValue());
        }

        //方法三
        Set<Map.Entry<String, Object>> entries = newmap.entrySet();
        for (Map.Entry<String, Object> entry : entries) {
           System.out.println(entry.getKey() + ",value为：" + entry.getValue());
        }