Sorting string value in a case-insensitive manner in Java 8

Question

How do I sort string values in case-insensitive order in the following?

List listofEmployees = Arrays.asList(
    new Employee(1, \"aaa\", Ar         


        

Answer 1

This is one of many ways:

listofEmployees.stream()
    .sorted((o1, o2) -> o1.getName().compareToIgnoreCase(o2.getName()))
    .forEach(s -> System.out.println(s.getName()));

Answer 2

You can specify it as the second argument to ignore cases:

Comparator.comparing(Employee::getName, String::compareToIgnoreCase).reversed()

Answer 3

It looks like there is a Comparator that orders String objects as by compareToIgnoreCase, you can read the documentation here: https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#CASE_INSENSITIVE_ORDER

Answer 4

As @Tree suggested in comments, one can use the java.text.Collator for a case-insensitive and locale-sensitive String comparison. The following shows how both case and accents could be ignored for US English:

Collator collator = Collator.getInstance(Locale.US);
collator.setStrength(Collator.PRIMARY);
listOfEmployees.sort(Comparator.comparing(Employee::getName, collator.reversed()));

When collator strength is set to PRIMARY, then only PRIMARY differences are considered significant during comparison. Therefore, the following Strings are considered equivalent:

if (collator.compare("abc", "ABC") == 0) {
    System.out.println("Strings are equivalent");
}

Answer 5

You can lowercase or uppercase it like this:

listofEmployees.stream()
               .sorted(Comparator.comparing((Employee e) -> e.getName()
                                 .toLowerCase()) // or toUpperCase
                                 .reversed())
               .forEach(s -> System.out.println(s.getName()));

Answer 6

Try this

Comparator.comparing(Employee::getName, String.CASE_INSENSITIVE_ORDER)