Incrementing counter in Stream foreach Java 8

Question

I'd like to increment a counter which is an AtomicInteger as I loop through using foreach

public class ConstructorTest {  public static void main(String[] args) {     AtomicInteger counter = new AtomicInteger(0);     List<Foo> fooList = Collections.synchronizedList(new ArrayList<Foo>());     List<String> userList = Collections.synchronizedList(new ArrayList<String>());     userList.add("username1_id1");     userList.add("username2_id2");      userList.stream().map(user -> new Foo(getName(user), getId(user))).forEach(fooList::add);     //how do I increment the counter in the above loop      fooList.forEach(user -> System.out.println(user.getName() + "   " + user.getId())); }  private static String getName(String user) {     return user.split("_")[0]; }  private static String getId(String user) {     return user.split("_")[1]; } } 

Answer 1

Depends on where you want to increment.

Either

userList.stream()         .map(user -> {                counter.getAndIncrement();                return new Foo(getName(user), getId(user));             })         .forEach(fooList::add); 

or

userList.stream()         .map(user -> new Foo(getName(user), getId(user)))         .forEach(foo -> {             fooList.add(foo);             counter.getAndIncrement();         });