I have the following qustion:
How can I convert the following code snipped to Java 8 lambda style?
List<String> tmpAdresses = new ArrayList<String>();
for (User user : users) {
tmpAdresses.add(user.getAdress());
}
Have no idea and started with the following:
List<String> tmpAdresses = users.stream().map((User user) -> user.getAdress());
You need to collect your Stream into a List:
List<String> adresses = users.stream()
.map(User::getAdress)
.collect(Collectors.toList());
For more information on the different Collectors visit the documentation.
User::getAdress is just another form of writing (User user) -> user.getAdress() which could as well be written as user -> user.getAdress() (because the type User will be inferred by the compiler)
.toList() instead of .collect(Collectors.toList()).It is extended your idea:
List<String> tmpAdresses = users.stream().map(user ->user.getAdress())
.collect(Collectors.toList())
One more way of using lambda collectors like above answers
List<String> tmpAdresses= users
.stream()
.collect(Collectors.mapping(User::getAddress, Collectors.toList()));
You can use this to convert Long to String:
List<String> ids = allListIDs.stream()
.map(listid-> String.valueOf(listid))
.collect(Collectors.toList());
User to its adress. Also how is your question different to the already existing ones?
Stringjust add.collect(Collectors.toList())tomap(...).(User user) -> user.getAddress()can be written asuser -> user.getAddress()or justUser::getAddress