Example: NonRepeatingElementsHashMap in Java

// NonRepeatingElementsHashMap
import java.util.HashMap;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        int[] arr = {5, 8, 2, 5, 8, 1, 9};

        System.out.println("Non-repeating elements (HashMap):");

        // Step 1: Create a HashMap to store element frequencies
        Map<Integer, Integer> frequencyMap = new HashMap<>();

        // Step 2: Iterate through the array and populate the frequency map
        for (int element : arr) {
            frequencyMap.put(element, frequencyMap.getOrDefault(element, 0) + 1);
        }

        // Step 3: Iterate through the array again to maintain original order
        //         and print elements with a frequency of 1
        for (int element : arr) {
            if (frequencyMap.get(element) == 1) {
                System.out.println(element);
            }
        }
        
        // Alternative Step 3: Iterate through the map (order not guaranteed)
        // for (Map.Entry<Integer, Integer> entry : frequencyMap.entrySet()) {
        //     if (entry.getValue() == 1) {
        //         System.out.println(entry.getKey());
        //     }
        // }
    }
}