With Guava you can use Function like -

private enum StudentToId implements Function<Student, Integer> {
        INSTANCE;

        @Override
        public Integer apply(Student input) {
            return input.getId();
        }
    }

and you can use this function to convert List of students to ids like -

Lists.transform(studentList, StudentToId.INSTANCE);

Surely it will loop in order to extract all ids, but remember guava methods returns view and Function will only be applied when you try to iterate over the List<Integer>
If you don't iterate, it will never apply the loop.

Note: Remember this is the view and if you want to iterate multiple times it will be better to copy the content in some other List<Integer> like

ImmutableList.copyOf(Iterables.transform(students, StudentToId.INSTANCE));

Thanks to Premraj for the alternative cool option, upvoted.

I have used apache CollectionUtils and BeanUtils. Accordingly, I am satisfied with performance of the following code:

List<Long> idList = (List<Long>) CollectionUtils.collect(objectList, 
                                    new BeanToPropertyValueTransformer("id"));

It is worth mentioning that, I will compare the performance of guava (Premraj provided) and collectionUtils I used above, and decide the faster one.

Java 8 lambda expression solution:

List<Integer> iDList = students.stream().map((student) -> student.getId()).collect(Collectors.toList());

If someone get here after a few years:

List<String> stringProperty = (List<String>) CollectionUtils.collect(listOfBeans, TransformerUtils.invokerTransformer("getProperty"));

The accepted answer can be written in a further shorter form in JDK 16 which includes a toList() method directly on Stream instances.

Java 16 solution

List<Integer> idList = students.stream().map(Student::getId).toList();

You can use Eclipse Collections for this purpose

Student first = new Student(1);
Student second = new Student(2);
Student third = new Student(3);

MutableList<Student> list = Lists.mutable.of(first, second, third);
List<Integer> result = list.collect(Student::getId);

System.out.println(result); // [1, 2, 3]