I have an ArrayList(Hashmap<String, String>) named users and each Hashmap<String, String> contains the profile of a user such as name,id,phone, etc...
I want to convert this ArrayList into some simple ArrayList. For example, I want to have an id ArrayList that contains all ids that can be found in the main ArrayList. Is there any function to do that?
You can write such a function with Streams:
public static List<String> getPropertyList(List<Map<String,String>> users, String key)
{
return users.stream()
.map(m -> m.get(key))
.collect(Collectors.toList());
}
Then call it with:
List<String> userIds = getPropertyList(users,"id");
List<String> userNames = getPropertyList(users,"name");
...
P.S. I changed the type of the list from ArrayList<HashMap<String,String>> to List<Map<String,String>>, since it's better to program to interfaces.
If you are using Java 7 or older, you'll need a loop:
public static List<String> getPropertyList(List<Map<String,String>> users, String key)
{
List<String> result = new ArrayList<String>();
for (Map<String,String> map : users) {
result.add(map.get(key));
}
return result;
}
