How to print two lists together using Stream API java 8?

Question

I have two lists as follow

List names = Arrays.asList(\"James\",\"John\",\"Fred\");
List ages = Arrays.asList(25,35,15);
         


        

Answer 1

The easiest way is to create an IntStream to generate the indices, and then map each index to the String you want to create.

IntStream.range(0, Math.min(names.size(), ages.size()))
         .mapToObj(i -> names.get(i)+":"+ages.get(i))
         .forEach(System.out::println);

Also you might be interested in this SO question Zipping streams using JDK8 with lambda (java.util.stream.Streams.zip), because this is the kind of functionality you're asking for.

Answer 2

My StreamEx library has some syntactic sugar for this case:

StreamEx.zip(names, ages, (name, age) -> name+":"+age).forEach(System.out::println)

Basically inside it's the same as in accepted answer. The only difference is that IllegalArgumentException will be thrown if size of lists differs.

Answer 3

While Alexis C. answer is correct, one would argue it is the easiest way to achieve requested behavior in Java 8. I propose:

int[] i = {0};
names.forEach(name -> {
    System.out.println(name + ages.get(i[0]++));
});

Or even without index:

List<Integer> agesCopy = new ArrayList<Integer>(ages);
names.forEach(name -> {
    System.out.println(name + agesCopy.remove(0));
});