How to modify elements inside List using stream and ignore last element?

November 23, 2021

I have the following list:

var list = Arrays.asList("a", "b", "c");

I want to achieve something like that:

// "a, "
// "b, "
// "c"

So I did that:

var formattedList = list.stream()
        .map(el -> el + ", ")
        .collect(Collectors.toList());

It is working almost fine:

// "a, "
// "b, "
// "c, "

but as you can see I don’t know how to "ommit" last element in my stream.

Could someone help me achieve that?

>Solution :

You can use String.join()

var list = Arrays.asList("a", "b", "c");
String.join(",", list) // returns a,b,c

I assumed you wanted to join the elements. But if you don’t, I think stream api is not suitable for this. Traditional iterator would work better. Because your requirement is based on index of the element. In streams, index information is not provided.