Junior — Middle

What methods can be used to eliminate duplicate elements in a list?

sobes.tech AI

Answer from AI

To eliminate duplicate elements in a list in Java, several methods can be used:

Using a Set — a set does not store duplicates, so you can create a HashSet from the list, and then convert it back to a list if needed:

List<String> list = Arrays.asList("a", "b", "a", "c");
Set<String> set = new HashSet<>(list);
List<String> uniqueList = new ArrayList<>(set);

Using Stream API (Java 8+) with the distinct() method:

List<String> list = Arrays.asList("a", "b", "a", "c");
List<String> uniqueList = list.stream()
                              .distinct()
                              .collect(Collectors.toList());

Manual iteration with a check for element existence — less efficient, but sometimes used.

Most often, the Stream API method is preferred because it is concise and convenient.

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