Top 20 Array Interview Questions In Java

532

Arrays are a fundamental part of Java programming, and interviewers often focus on them. Did you know that a majority of tech companies in India, like Infosys, TCS, and Wipro, ask about arrays in Java interviews? This highlights the importance of understanding array concepts. In this article, we present the top 20+ array interview questions in Java, along with their answers. 

This guide will prepare you to tackle questions on array and increase your chances of landing the job.

Array Programming Interview Questions in Java for Freshers

Here are some commonly asked array interview questions in Java for freshers and their answers.

1. What is an array in Java?

An array in Java is a data structure that stores a fixed-size sequential collection of elements of the same type. It provides random access to elements based on an index.

2. How do you declare an array in Java?

You can declare an array in Java using the following syntax:

int[] array;

3. What is the difference between an array and an ArrayList in Java?

An array in Java is a fixed-size data structure, whereas an ArrayList is a dynamic-size data structure. Arrays can store primitives and objects, while ArrayList can only store objects.

4. Can you change the size of an array once it is created in Java?

No, the size of an array in Java is fixed once it is created. You cannot change it dynamically. If you need to resize an array, you would need to create a new array and copy the elements from the old array.

5. What is the length of an array in Java?

The length of an array in Java is the number of elements it contains. You can obtain the length of an array using the length property.

6. Can an array contain elements of different data types in Java?

No, in Java, arrays can only contain elements of the same data type. Once the data type of an array is defined, it can only hold elements of that specific type.

7. What is the default value of an array in Java?

The default value for array elements in Java depends on their type: 0 for numeric types, false for boolean, ‘\u0000’ for char, and null for reference types.

Also Read - Top 20+ Java Collections Interview Questions With Answers

Array Programming Interview Questions in Java for Experienced

Here are some important Java array programming interview questions and answers for experienced candidates. 

8. Explain the concept of dynamic arrays and their advantages over static arrays.

Dynamic arrays, like ArrayList in Java, can resize themselves dynamically, allowing flexible storage. Unlike static arrays, they eliminate the need for pre-allocation and provide efficient memory usage.

9. What are some common operations performed on arrays?

Common operations on arrays include accessing elements by index, modifying elements, finding the maximum or minimum value, sorting, searching for elements, and iterating over the elements.

10. What is the difference between an array and a linked list?

An array is a fixed-size data structure with elements stored in contiguous memory locations, allowing random access. 

A linked list is a dynamic-size data structure where elements are stored in nodes with references to the next node, suitable for frequent insertions and deletions.

Also Read - Top 35+ NodeJS Interview Questions and Answers

11. How do you find the median of an array in Java?

To find the median of an array, you first sort the array and then find the middle element. If the array has an even number of elements, you take the average of the two middle elements.

12. What are the benefits of heap over sorted arrays?

Heap offers constant-time insertion and deletion, which is crucial for dynamic data structures like priority queues. 

In contrast, maintaining a sorted array requires costly reordering after insertions and deletions, making heap more efficient for operations like insertion and deletion.

Array in Java Interview Questions (Advanced)

You can also expect these advanced-level array in Java interview questions.

13. How does Java handle multi-dimensional arrays, and what are their practical applications?

Java supports multi-dimensional arrays, allowing storage of data in matrices or tables. They are used in applications like image processing, game development, and scientific computations for organizing and manipulating data efficiently.

14. Discuss the concept of “ragged arrays” in Java and their use cases.

Ragged arrays are arrays of arrays where sub-arrays can have different lengths. They are useful for representing irregular data structures like jagged matrices, sparse data sets, or tree-like structures efficiently.

15. How can you efficiently remove duplicates from an array in Java?

You can remove duplicates from an array by using a Set data structure to store unique elements while iterating through the array. Sets automatically eliminate duplicates, providing an efficient solution.

16. Explain the concept of “array manipulation” in Java and its applications.

Array manipulation involves performing various operations like addition, deletion, or modification of elements within an array. It’s widely used in algorithms, data processing, and numerical computations to transform and analyze array data efficiently.

Also Read - Top 25+ Java Data Structures Interview Questions With Answers

Array Coding Interview Questions in Java

These are some commonly asked coding-related arrays practice questions in Java and their answers. 

17. Write a Java program to find the maximum element in an array.

public class MaxElementInArray {

    public static void main(String[] args) {

        int[] array = {1, 5, 3, 7, 2};

        int max = array[0];

        for (int num : array) {

            if (num > max) {

                max = num;

            }

        }

        System.out.println(“Maximum element: ” + max);

    }

}

18. Write a Java program to reverse an array.

This is one of the most commonly-asked array program in Java for interviews.

public class ReverseArray {

    public static void main(String[] args) {

        int[] array = {1, 2, 3, 4, 5};

        int start = 0;

        int end = array.length – 1;

        while (start < end) {

            int temp = array[start];

            array[start] = array[end];

            array[end] = temp;

            start++;

            end–;

        }

        System.out.println(“Reversed array: ” + Arrays.toString(array));

    }

}

19. Write a Java program to find if an array contains a certain value.

public class FindValueInArray {

    public static void main(String[] args) {

        int[] array = {1, 2, 3, 4, 5};

        int value = 3;

        boolean found = false;

        for (int num : array) {

            if (num == value) {

                found = true;

                break;

            }

        }

        System.out.println(“Value ” + value + ” found: ” + found);

    }

}

20. Write a Java program to find the sum of all elements in an array.

public class SumOfElements {

    public static void main(String[] args) {

        int[] array = {1, 2, 3, 4, 5};

        int sum = 0;

        for (int num : array) {

            sum += num;

        }

        System.out.println(“Sum of elements: ” + sum);

    }

}

21. Write a Java program to remove duplicates from an array.

import java.util.*;

public class RemoveDuplicates {

    public static void main(String[] args) {

        int[] array = {1, 2, 3, 2, 4, 5, 1};

        Set<Integer> set = new HashSet<>();

        for (int num : array) {

            set.add(num);

        }

        System.out.println(“Array without duplicates: ” + set);

    }

}

Understanding this array interview programs in Java is essential for excelling in technical interviews.

Also Read - Top 25+ Interview Questions On String in Java with Answers

Wrapping Up

These top 20+ array interview questions in Java will help you easily prepare for your upcoming programming interview. Make sure you practice these questions thoroughly to increase your chances of landing your dream job.Speaking of jobs, if you are still looking for career opportunities, visit Hirist. It is an online job portal specially designed for the tech sector. Here, you can easily find the latest job openings among the top IT companies in India.