Let’s see how to get unique values from ArrayList. Convert ArrayList to HashSet to insert duplicate values in ArrayList but on the other hand, HashSet is not allowing to insert any duplicate value. While converting ArrayList to HashSet all the duplicate values are removed and as a result, unique values are obtained.
Example:
INPUT : ArrayList = [a, b, c, b, d, a, c] OUTPUT: Unique = [a, b, c, d] INPUT : ArrayList = [1, 5, 2, 4, 3, 4, 5] OUTPUT: Unique = [1, 2, 3, 4, 5]
Approach:
- Create a ArrarList.
- Add elements in ArrayList.
- Create HashSet and pass in HashSet constructor.
- Print HashSet object.
Below is the implementation of the above approach:
Java
// Get Unique Values from ArrayList in Javaimport java.util.ArrayList;import java.util.HashSet; public class GFG { public static void main(String[] args) { // Create ArrayList ArrayList<String> ArrList = new ArrayList<String>(); // add values in ArrayList ArrList.add("a"); ArrList.add("b"); ArrList.add("c"); ArrList.add("b"); ArrList.add("d"); ArrList.add("a"); ArrList.add("c"); // display original ArrayList System.out.println("Original ArrayList is : " + ArrList); // convert ArrayList to HastSet. HashSet<String> hset = new HashSet<String>(ArrList); // display HastSet System.out.println("ArrayList Unique Values is : " + hset); }} |
Output
Original ArrayList is : [a, b, c, b, d, a, c] ArrayList Unique Values is : [a, b, c, d]
Time Complexity: O(n), where n is the length of the original ArrayList.
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