CODEWITHSUNDEEP
java-8
R.S
R.S

Reputation: 41

Using java8 how can we sort elements starting from the second element to till last?

Using java8 how can we sort elements starting from the second element to till last?

  list.stream().filter(student -> student.getAge()!=15).sorted(Comparator.comparing(student->student.getAge())).collect(Collectors.toList());

The final sorted list should contain all the elements including first one.

I have tried above code snippet:

Here i dont want to touch first element.The above code is sorting from 2nd element to till last element.the problem is i am not getting first element(age =15) in output.

If i dont apply filter it will sort all the elements and i will loose first element, which should not happen.

Please help me on this.Thanks in advance.

Upvotes: 4

Views: 743

Answers (4)

Holger
Holger

Reputation: 298143

Rethink whether the Stream API is the best choice here:

List<Student> result = new ArrayList<>(list);
result.subList(1, list.size()).sort(Comparator.comparing(Student::getAge));

Note that if the source list is mutable and you don’t need the original list order, you can do the operation directly on the source list using only the second line of above code snippet.

Upvotes: 2

Eugene
Eugene

Reputation: 120848

 List<Student> result = Stream.concat(
            list.stream().findFirst().map(Stream::of).orElse(Stream.empty()),
            list.stream().skip(1).sorted(Comparator.comparing(Student::getAge)))
            .collect(Collectors.toList());

    System.out.println(result);

Upvotes: 4

fps
fps

Reputation: 34460

You could use List.subList method to skip the first element of the list:

List<Student> result = list.isEmpty() ? new ArrayList<>() : // or just list
    Stream.concat(
        Stream.of(list.get(0)),
        list.subList(1, list.size()).stream()
            .sorted(Comparator.comparing(Student::getAge)))
    .collect(Collectors.toList());

Upvotes: 2

developer_hatch
developer_hatch

Reputation: 16224

Try this, you can filter the first element after procesing the whole list:

Stream.concat(
        Stream.of(list.stream().findFirst().get()),
        list.stream().skip(1).sorted(Comparator.comparing(Student::getAge)))
        .collect(Collectors.toList()).skip(1);

Upvotes: 0

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