Iterate a Set

Here in this article we will see a few ways to iterate a map and their performances.

public class IterateSet { public static void main(String[] args) { //example Set Set<String> set = new HashSet<>(); set.add("Jack"); set.add("John"); set.add("Joe"); set.add("Josh"); long startTime = System.nanoTime(); long endTime = System.nanoTime(); //using iterator System.out.println("Using Iterator"); startTime = System.nanoTime(); Iterator<String> setIterator = set.iterator(); while(setIterator.hasNext()){ System.out.println(setIterator.next()); } endTime = System.nanoTime(); long durationIterator = (endTime - startTime); //using lambda System.out.println("Using Lambda"); startTime = System.nanoTime(); set.forEach((s) -> System.out.println(s)); endTime = System.nanoTime(); long durationLambda = (endTime - startTime); //using Stream API System.out.println("Using Stream API"); startTime = System.nanoTime(); set.stream().forEach((s) -> System.out.println(s)); endTime = System.nanoTime(); long durationStreamAPI = (endTime - startTime); //using Split Iterator (not recommended) System.out.println("Using Split Iterator"); startTime = System.nanoTime(); Spliterator<String> splitIterator = set.spliterator(); splitIterator.forEachRemaining((s) -> System.out.println(s)); endTime = System.nanoTime(); long durationSplitIterator = (endTime - startTime); //time calculations System.out.println("Iterator Duration:" + durationIterator); System.out.println("Lamda Duration:" + durationLambda); System.out.println("Stream API:" + durationStreamAPI); System.out.println("Split Iterator:"+ durationSplitIterator); } } The code is self explanatory. The result of the durations are: Iterator Duration:495287 Lamda Duration:50207470 Stream API:2427392 Split Iterator:567294 We can see the Lambda takes the longest while Iterator is the fastest. Apart from this there is the traditional age-old enhanced for loop.