Top 10 Java Array Interview Questions (With Solutions)

Array-based questions are one of the most frequently asked topics in Java interviews.

Array questions are a key part of technical interviews and test your problem-solving skills.

If you're preparing for coding interviews, practicing array problems is essential to improve logic and problem-solving skills.

Written by Shivkumar Udas – Engineering student sharing practical Java guides for beginners.

💡 Why Array Questions Matter

Arrays are fundamental data structures used in almost every program, making them very important for interviews.

1. Find Largest Element in Array

int[] arr = {10, 20, 5, 40};
int max = arr[0];

for(int i = 1; i < arr.length; i++) {
    if(arr[i] > max) {
        max = arr[i];
    }
}

System.out.println("Largest: " + max);

Time Complexity: O(n)

2. Find Smallest Element

int min = arr[0];

for(int i = 1; i < arr.length; i++) {
    if(arr[i] < min) {
        min = arr[i];
    }
}

Time Complexity: O(n)

3. Reverse an Array

int[] arr = {1,2,3,4};
for(int i = 0; i < arr.length / 2; i++) {
    int temp = arr[i];
    arr[i] = arr[arr.length - i - 1];
    arr[arr.length - i - 1] = temp;
}

Time Complexity: O(n)

4. Sum of Array Elements

int sum = 0;
for(int num : arr) {
    sum += num;
}
System.out.println(sum);

Time Complexity: O(n)

5. Find Duplicate Elements

for(int i = 0; i < arr.length; i++) {
    for(int j = i + 1; j < arr.length; j++) {
        if(arr[i] == arr[j]) {
            System.out.println(arr[j]);
        }
    }
}

Time Complexity: O(n²)

6. Sort Array (Ascending)

import java.util.Arrays;

Arrays.sort(arr);
System.out.println(Arrays.toString(arr));

Time Complexity: O(n log n)

7. Find Second Largest Element

int first = Integer.MIN_VALUE, second = Integer.MIN_VALUE;

for(int num : arr) {
    if(num > first) {
        second = first;
        first = num;
    } else if(num > second && num != first) {
        second = num;
    }
}
System.out.println(second);

Time Complexity: O(n)

8. Check if Array is Sorted

boolean sorted = true;

for(int i = 1; i < arr.length; i++) {
    if(arr[i] < arr[i-1]) {
        sorted = false;
        break;
    }
}
System.out.println(sorted);

Time Complexity: O(n)

9. Count Even and Odd Numbers

int even = 0, odd = 0;

for(int num : arr) {
    if(num % 2 == 0) even++;
    else odd++;
}

Time Complexity: O(n)

10. Remove Duplicate Elements

import java.util.HashSet;

HashSet set = new HashSet<>();
for(int num : arr) {
    set.add(num);
}
System.out.println(set);

Time Complexity: O(n)

📌 Most Important Array Topics

• Searching
• Sorting
• Duplicates
• Max/Min

🎯 Interview Tip

Focus on solving problems step by step. Many interviewers ask follow-up optimizations.

Understanding logic is more important than memorizing code.

🔗 Related Guides

• Java Coding Programs
• Collections Framework
• Java Interview Questions

🎯 Conclusion

Array questions are essential for Java interviews and help improve your problem-solving skills.

Practice regularly and focus on optimization.