Array traversal in Java - Practice Problems & Coding Challenges

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Challenge - 5 Problems

💻 code output

intermediate

Output of nested array traversal

What is the output of the following Java code that traverses a 2D array?

Java

public class Main {
    public static void main(String[] args) {
        int[][] matrix = {{1, 2}, {3, 4}};
        int sum = 0;
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                sum += matrix[i][j];
            }
        }
        System.out.println(sum);
    }
}

A 10

B 24

C 0

D Compilation error

💻 code output

intermediate

Output of enhanced for-loop traversal

What will be printed by this Java code that uses an enhanced for-loop to traverse an array?

Java

public class Main {
    public static void main(String[] args) {
        String[] fruits = {"apple", "banana", "cherry"};
        for (String fruit : fruits) {
            System.out.print(fruit.charAt(0));
        }
    }
}

A Compilation error

B applebananacherry

C abc\n

D abc

🧠 conceptual

advanced

Understanding array traversal with break statement

What is the output of this Java code that traverses an array and uses a break statement?

Java

public class Main {
    public static void main(String[] args) {
        int[] numbers = {5, 10, 15, 20};
        int total = 0;
        for (int num : numbers) {
            if (num == 15) {
                break;
            }
            total += num;
        }
        System.out.println(total);
    }
}

A 0

B 30

C 15

D 50

🔧 debug

advanced

Identify the error in array traversal

What error will this Java code produce when run?

Java

public class Main {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3};
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}

A ArrayIndexOutOfBoundsException

B NullPointerException

C Compilation error

D No output, infinite loop

🚀 application

expert

Calculate the product of all even numbers in an array

What is the output of this Java program that multiplies all even numbers in an array?

Java

public class Main {
    public static void main(String[] args) {
        int[] nums = {2, 3, 4, 5, 6};
        int product = 1;
        for (int n : nums) {
            if (n % 2 == 0) {
                product *= n;
            }
        }
        System.out.println(product);
    }
}

A 120

B 48

C 0

D 15