java8 achieve traverse map, map rotation list, list turn map

1. Traversing the map

   map.forEach((k, v) -> System.out.println("key:value = " + k + ":" + v));

    

2. map transfer list

   map.entrySet().stream().map(e -> new Person(e.getKey(),e.getValue())).collect(Collectors.toList());

    

3. turn map list

    Map<Integer, String> result1 = list.stream().collect(
                   Collectors.toMap(Hosting::getId, Hosting::getName));