从地图获取条目集

Question

Given a map such as:

Map<String, Integer> = new Hashmap<String, Integer>;

How can I get a Collection<Integer> (any implementation of Collection would do) of the entrySet? Doing .entrySet() doesn't seem to work.

Answer 1

If you want to get just the map values you can use the values() method. The Javadoc page is here .

This is because your requirement is a Collection of Integers and the map values are of Integer type.

entrySet returns a collection of Map.Entry , each instance of which contains both the key and value that make up the entry, so if you want both the key and value, use entrySet() like so

Set<Map.Entry<String, Integer>> entries = map.entrySet()

Answer 2

That depends on if you truly want a SET. If you want a true Set you must do:

Set mySet = new HashSet(map.values());

Notice that values gives a Collection which can have duplicate entries.