Access all elements after stream filter

Question

My task is to filter an array, change the remaining elements and return the array with both the changed and unchanged values. My code:

return Arrays.stream(sentence.split(" "))
    .filter(/* do some filter to each value */)
    .map(/* map this value*/)
    .collect(Collectors.joining());

How can I return an array of the changed and unchanged values?

Answer 1

filter removes elements. If you don't want to remove elements, but rather just change some of them, you can use ?: or if-else inside map to selectively change elements.

For example:

System.out.println(Stream.of("abc", "def", "ghi")
    .map(a -> a.equals("def") ? "xyz" : a)
    .collect(Collectors.toList()));

Or:

System.out.println(Stream.of("abc", "def", "ghi")
    .map(a -> {
       if (a.equals("def"))
          return "xyz";
       else
          return a;
    })
    .collect(Collectors.toList()));

This will only change the element which equals def to xyz (for each other element, it will simply keep that element as is) and the output will be:

[abc, xyz, ghi]

Answer 2

We can achieve this without stream also.

List<String> list = Arrays.asList("abc", "def", "ghi");
list.replaceAll(s -> s.equals("def") ? "xyz" : s);
System.out.println(list);

Output

[abc, xyz, ghi]