Convert List of Strings into Map using Java-8 Streams API

Question

I have List

List<String> cars = Arrays.asList("Ford", "Focus", "Toyota", "Yaris","Nissan", "Micra", "Honda", "Civic");

Now, can I convert this List into Map where I get ford = focus, Toyota = yaris, Nisan = Micra, Honda = Civic using Java 8 Streams API?

@nullpointer not really, its a completely different problem (mapping elements together vs mapping elements with something else) — Paul Lemarchand
– Paul Lemarchand, Commented Oct 14, 2017 at 1:43

Paul Lemarchand · Accepted Answer · 2017-10-14 00:50:44Z

3

Here is an example on how you could do it :

 Map<String, String> carsMap =
            IntStream.iterate(0, i -> i + 2).limit(cars.size() / 2)
                    .boxed()
                    .collect(Collectors.toMap(i -> cars.get(i), i -> cars.get(i + 1)));

Basically, just iterates over every 2 elements and maps it with the next one.
Note that if the number of elements is not even, it won't take into consideration the last element.

answered Oct 14, 2017 at 0:50

Paul Lemarchand

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2 Comments

meticulous_guy Over a year ago

Thanks a lot, Paul for the help. I tried my problem with solution suggested by @nullpointer. But it is way to confusing for people who has less knowledge of how lambda works. And my problem is entirely different than the similar questions asked here before. Moreover, I wasn't hoping to get answer of my question as I find moderators here extremely bossy and bully. But you saved my life. Thanks again. :)

Paul Lemarchand Over a year ago

@meticulous_guy :)

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