Java stream remove first three elements

Question

I have list of object sorted by student id:

List<Student> arraylist = new ArrayList<>();
arraylist.add(new Student(1, "Chaitanya", 26));
arraylist.add(new Student(2, "Chaitanya", 26));
arraylist.add(new Student(3, "Rahul", 24));
arraylist.add(new Student(4, "Ajeet", 32));
arraylist.add(new Student(5, "Chaitanya", 26));
arraylist.add(new Student(6, "Chaitanya", 26));

I would like to use stream and remove only first three elements where student age equals 26. Could you please help me with this.

Answer 1

You can use filter and skip as :

List<Student> finalList = arraylist.stream()
        .filter(a -> a.getAge() == 26) // filters the students with age 26
        .skip(3) // skips the first 3 
        .collect(Collectors.toList());

This will result in listing Students with age equal to 26 while at the same time skipping first three occurrences of such students.

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On the other hand, if you just want to exclude those three students from the complete list, you can also do it as:

List<Student> allStudentsExcludingFirstThreeOfAge26 = Stream.concat(
            arraylist.stream().filter(a -> a.getAge() != 26),
            arraylist.stream().filter(a -> a.getAge() == 26).skip(3))
        .collect(Collectors.toList());

Do note, that this could result in changing the original order of the list.