Print a 2D Array or Matrix in Java

A 2D array in Java is an array of arrays that is commonly used to represent a matrix. To print all elements of a 2D array, we can use nested loops or built-in methods from the Arrays class.

Illustration:

Input: mat[][] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}
Output: 1 2 3
4 5 6
7 8 9

Input: mat[][] = {{10, 20}, {30, 40}}
Output: 10 20
30 40

Different Ways to Print a 2D Array in Java

We can print a 2D array using the following approaches:

1. Using Nested for Loop

The simplest way to print a 2D array is by using two for loops. The outer loop traverses the rows, while the inner loop traverses the elements of each row.

class GFG {

    static void print2D(int[][] mat) {

        // Traverse rows
        for (int i = 0; i < mat.length; i++) {

            // Traverse columns
            for (int j = 0; j < mat[i].length; j++) {
                System.out.print(mat[i][j] + " ");
            }

            System.out.println();
        }
    }

    public static void main(String[] args) {

        int[][] mat = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        print2D(mat);
    }
}

1 2 3 
4 5 6 
7 8 9 

Explanation

• mat.length gives the number of rows.
• mat[i].length gives the number of elements in the current row.
• The outer loop moves through each row.
• The inner loop prints each element of the current row.

2. Using Nested for-each Loop

The nested for-each loop provides a simpler way to traverse the rows and elements of a 2D array without using indexes.

class GFG {

    static void print2D(int[][] mat) {

        for (int[] row : mat) {

            for (int value : row) {
                System.out.print(value + " ");
            }

            System.out.println();
        }
    }

    public static void main(String[] args) {

        int[][] mat = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        print2D(mat);
    }
}

1 2 3 
4 5 6 
7 8 9 

Explanation

• The outer for-each loop gets each row.
• The inner for-each loop gets each element from the current row.
• System.out.println() moves the output to the next line after each row.

3. Using Arrays.toString()

The Arrays.toString() method can be used to convert each one-dimensional row into a readable string. We can call it for every row of the 2D array. 

import java.util.Arrays;

class GFG {

    public static void main(String[] args) {

        int[][] mat = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        for (int[] row : mat) {
            System.out.println(Arrays.toString(row));
        }
    }
}

[1, 2, 3]
[4, 5, 6]
[7, 8, 9]

Explanation

• Arrays.toString(row) converts each one-dimensional row into a string.
• Each row is printed on a separate line.
• This approach is useful when we want a readable representation of each row.

4. Using Arrays.deepToString()

The Arrays.deepToString() method can directly convert a multidimensional array into a readable string representation.

import java.util.Arrays;

class GFG {

    public static void main(String[] args) {

        int[][] mat = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        System.out.println(Arrays.deepToString(mat));
    }
}

[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

Explanation

• Arrays.deepToString() is designed for multidimensional arrays.
• It processes nested arrays automatically.
• It is useful when we want to print the entire 2D array in a single statement.