遍历Map的两种方式

遍历Map的两种方式：
准备一个Map

Map<String, String> map = new HashMap<>();
        map.put("a", "aa");
        map.put("b", "bb");
        map.put("c", "cc");
        map.put("d", "dd");
        map.put("e", "ee");
        map.put("f", "ff");

1. 使用entrySet进行遍历

Set<Map.Entry<String, String>> set = map.entrySet();
        for (Map.Entry<String, String> entry : set) {
            System.out.println(entry.getKey() + "__" + entry.getValue());
        }

2. 使用Iterator进行遍历

 Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, String> entry = iterator.next();
            System.out.println(entry.getKey() + "__" + entry.getValue());
        }

获取所有的key

Set<String> keySet = map.keySet();
        for (String s : keySet) {
            System.out.println(s);
        }

获取所有的value

Collection<String> values = map.values();
        for (String value : values) {
            System.out.println(value);
        }