Two-dimensional arrays are one of the most commonly used data structures in Java for storing data in rows and columns. They are widely used in matrix operations, game boards, image processing, spreadsheets, and many other applications. Practicing common two-dimensional array programs helps you understand array traversal, nested loops, and matrix manipulation techniques. In this article, we will explore some frequently asked two-dimensional array programs with complete code, output, and explanations.
 

Table of Contents

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Print All Elements of a Two-Dimensional Array

Given a two-dimensional array containing integer values, write a Java program to display all the elements in matrix format. Each row should be printed on a separate line.

// Java program to print all elements of 
// two-dimensional array
public class PrintMatrix 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {10, 20, 30},
            {40, 50, 60},
            {70, 80, 90}
        };

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

Output:

10 20 30
40 50 60
70 80 90

Explanation:
The outer loop traverses each row, while the inner loop traverses each column and prints the elements.

Find the Sum of All Elements

Given a two-dimensional array of integers, write a Java program to calculate the sum of all elements present in the array.

// Java program to find sum of all elements
public class SumMatrixElements 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        int sum = 0;

        for(int i = 0; i  arr.length; i++) 
        {
            for(int j = 0; j  arr[i].length; j++) 
            {
                sum += arr[i][j];
            }
        }

        System.out.println("Sum = " + sum);
    }
}

Output:

Sum = 45

Explanation:
The program visits every element of the matrix and adds it to the sum variable.

Find the Largest Element

Given a two-dimensional array, write a Java program to identify and display the largest element stored in the array.

// Java program to find the largest element
public class LargestElement 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {12, 45, 7},
            {89, 34, 21},
            {5, 99, 15}
        };

        int largest = arr[0][0];

        for(int i = 0; i  arr.length; i++) 
        {
            for(int j = 0; j  arr[i].length; j++) 
            {
                if(arr[i][j]  largest) 
                {
                    largest = arr[i][j];
                }
            }
        }

        System.out.println("Largest Element = " + largest);
    }
}

Output:

Largest Element = 99

Explanation:
The program compares every element with the current largest value and updates it whenever a larger value is found.

Find the Smallest Element

Given a two-dimensional array of integers, write a Java program to find and display the smallest element present in the array.

// Java program to find th
// smallest element
public class SmallestElement 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {12, 45, 7},
            {89, 34, 21},
            {5, 99, 15}
        };

        int smallest = arr[0][0];

        for(int i = 0; i  arr.length; i++) 
        {
            for(int j = 0; j  arr[i].length; j++) 
            {
                if(arr[i][j]  smallest) 
                {
                    smallest = arr[i][j];
                }
            }
        }

        System.out.println("Smallest Element = " + smallest);
    }
}

Output:

Smallest Element = 5

Calculate Row-Wise Sum

Given a matrix of integers, write a Java program to calculate the sum of elements in each row and display the row-wise sums separately.

// Java program to calculate 
// row-wise sum
public class RowWiseSum 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        for(int i = 0; i  arr.length; i++) 
        {
            int rowSum = 0;

            for(int j = 0; j  arr[i].length; j++) 
            {
                rowSum += arr[i][j];
            }

            System.out.println("Row " + (i + 1) + " Sum = " + rowSum);
        }
    }
}

Output:

Row 1 Sum = 6
Row 2 Sum = 15
Row 3 Sum = 24

Calculate Column-Wise Sum

Given a two-dimensional array, write a Java program to calculate the sum of elements in each column and display the result for every column.

// Java program to calculate 
// column-wise sum
public class ColumnWiseSum 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        for(int j = 0; j  arr[0].length; j++) 
        {
            int colSum = 0;

            for(int i = 0; i  arr.length; i++) 
            {
                colSum += arr[i][j];
            }

            System.out.println("Column " + (j + 1) + " Sum = " + colSum);
        }
    }
}

Output:

Column 1 Sum = 12
Column 2 Sum = 15
Column 3 Sum = 18

Find the Sum of Main Diagonal Elements

Given a square matrix, write a Java program to calculate the sum of all elements present on the main diagonal.

// Java program to find sum of
// main diagonal elements
public class DiagonalSum 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        int sum = 0;

        for(int i = 0; i  arr.length; i++) 
        {
            sum += arr[i][i];
        }

        System.out.println("Diagonal Sum = " + sum);
    }
}

Output:

Diagonal Sum = 15

Find the Transpose of a Matrix

Given a matrix, write a Java program to find and display its transpose.

// Java program to find transpose of
// a matrix
public class MatrixTranspose 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {1, 2, 3},
            {4, 5, 6}
        };

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

Output:

1 4
2 5
3 6

Search an Element in a Matrix

Given a two-dimensional array and a target value, write a Java program to search for the target element in the matrix.

// Java program to search an element
// in the matrix
public class SearchElement 
{
    public static void main(String[] args) 
    {
        int[][] arr = 
        {
            {10, 20, 30},
            {40, 50, 60},
            {70, 80, 90}
        };

        int target = 50;
        boolean found = false;

        for(int i = 0; i  arr.length; i++) 
        {
            for(int j = 0; j  arr[i].length; j++) 
            {
                if(arr[i][j] == target) 
                {
                    found = true;
                }
            }
        }

        if(found) 
        {
            System.out.println("Element Found");
        } 
        else 
        {
            System.out.println("Element Not Found");
        }
    }
}

Output:

Element Found

Conclusion

Two-dimensional arrays are essential for working with matrix-like data in Java. Programs such as matrix traversal, finding sums, searching elements, calculating row-wise and column-wise totals, and performing transpose operations help build a strong understanding of array manipulation. By practicing these common programs, you can improve your coding skills and prepare for more advanced programming challenges.

Frequently Asked Questions

1. What is a two-dimensional array in Java?

A two-dimensional array is an array of arrays that stores data in rows and columns.

2. Why are nested loops used with two-dimensional arrays?

Nested loops are used because the array contains both rows and columns that must be traversed separately.

3. What is the transpose of a matrix?

A transpose is obtained by interchanging the rows and columns of a matrix.

4. Can two-dimensional arrays have different row sizes?

Yes, Java supports jagged arrays where each row can have a different number of elements.

5. Where are two-dimensional arrays used in real-world applications?

They are used in spreadsheets, game boards, image processing, scientific calculations, and matrix operations.