Remove duplicates from a list and keep the order

Description: Remove the duplicates from [4, 7, 4, 1, 7, 9, 1] and keep the order of the first appearance.

Hint:

• A LinkedHashSet keeps the insert order. Or use stream().distinct().

---

Solution

import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<Integer> numbers = List.of(4, 7, 4, 1, 7, 9, 1);

        List<Integer> a = new ArrayList<>(new LinkedHashSet<>(numbers));
        List<Integer> b = numbers.stream().distinct().toList();

        System.out.println(a);
        System.out.println(b);
    }
}

How it works

• A set does not allow duplicates, and the linked version remembers the order.

Read HashSet and LinkedList.

• Previous Exercise
• Next Exercise

---

Tutorials
No Content Found.

Exercises & Assignments
No Content Found.

Interview Questions & Answers
No Content Found.