Java Program to remove duplicate element in an Array

We can remove duplicate element in an array by 2 ways: using temporary array or using separate index. To remove the duplicate element from array, the array must be in sorted order. If array is not sorted, you can sort it by calling Arrays.sort(arr) method.

1) Remove Duplicate Element in Array using Temporary Array

Output:

10 20 30 40 50 

2) Remove Duplicate Element in Array using separate index

Output:

10 20 30 40 50 

Remove Duplicate Elements in Unsorted Array

If you have unsorted array, you need to sort it first. To do so, use Arrays.sort(arr) method.

Output:

10 20 30 40 50 70 90 

Java Program to remove duplicate element in an Array MCQ

1. Which Java data structure is most efficient for removing duplicates from an array?

1. LinkedList
2. TreeSet
3. ArrayList
4. HashSet

2. After removing duplicates from an array, what can be done to retain the original order of elements?

1. Use a TreeSet.
2. Use a HashMap.
3. Use a LinkedHashSet.
4. Sort the array.

3. What will be the output of the following code?

1. [1, 2, 3, 4]
2. [1, 2, 2, 3, 4, 4]
3. [4, 3, 2, 1]
4. Compilation error

4. Which method can be used to convert a Set back to an array?

1. toArray()
2. toList()
3. toSet()
4. toMap()

5. How can you remove duplicates from an array without using additional data structures?

1. By sorting the array and then removing duplicates.
2. By using recursion.
3. By using nested loops to check for duplicates.
4. Both A and C.