Print a 2 D Array or Matrix in Java

Prerequisites: Arrays in Java, Array Declarations in Java (Single and Multidimensional)

Method 1 (Simple Traversal) 

We can find the number of rows in a matrix mat[][] using mat.length. To find the number of columns in i-th row, we use mat[i].length.

Java

// Java program to print the elements of
// a 2 D array or matrix
import java.io.*;
class GFG {

    public static void print2D(int mat[][])
    {
        // Loop through all rows
        for (int i = 0; i < mat.length; i++)

            // Loop through all elements of current row
            for (int j = 0; j < mat[i].length; j++)
                System.out.print(mat[i][j] + " ");
    }

    public static void main(String args[])
        throws IOException
    {
        int mat[][] = { { 1, 2, 3, 4 },
                        { 5, 6, 7, 8 },
                        { 9, 10, 11, 12 } };
        print2D(mat);
    }
}

Output

1 2 3 4 5 6 7 8 9 10 11 12 

Complexity of the above method:

Time Complexity: O(N*M) where N is the number of rows in the matrix and M is the number of columns in the matrix.
Auxiliary Space: O(1)

Method 2 (Using for-each loop) 

This is similar to the above. Instead of simple for loops, we use for each loop here. 

Java

// Java program to print the elements of
// a 2 D array or matrix using for-each
import java.io.*;
class GFG {

    public static void print2D(int mat[][])
    {
        // Loop through all rows
        for (int[] row : mat)

            // Loop through all columns of current row
            for (int x : row)
                System.out.print(x + " ");
    }

    public static void main(String args[])
        throws IOException
    {
        int mat[][] = { { 1, 2, 3, 4 },
                        { 5, 6, 7, 8 },
                        { 9, 10, 11, 12 } };
        print2D(mat);
    }
}

Output

1 2 3 4 5 6 7 8 9 10 11 12 

Complexity of the above Method:

Time Complexity: O(N*M) where N is the number of rows in the matrix and M is the number of columns in the matrix.
Auxiliary Space: O(1)

Method 3 (Prints in matrix style Using Arrays.toString())

Arrays.toString(row) converts the complete row is converted as a string and then each row is printed in a separate line. 

Java

// Java program to print the elements of
// a 2 D array or matrix using toString()
import java.io.*;
import java.util.*;

// Driver Class
class GFG {

    public static void print2D(int mat[][])
    {
        // Loop through all rows
        for (int[] row : mat)

            // converting each row as string
            // and then printing in a separate line
            System.out.println(Arrays.toString(row));
    }

    public static void main(String args[])
        throws IOException
    {
        int mat[][] = { { 1, 2, 3, 4 },
                        { 5, 6, 7, 8 },
                        { 9, 10, 11, 12 } };
        print2D(mat);
    }
}

Output

[1, 2, 3, 4]
[5, 6, 7, 8]
[9, 10, 11, 12]

Complexity of the above Method:

Time Complexity: O(N*M)
Auxiliary Space: O(1)

Method 4 (Prints in matrix style Using Arrays.deepToString())

Arrays.deepToString(int[][]) converts  2D array to string in a single step.

Java

// Java program to print the elements of
// a 2 D array or matrix using deepToString()
import java.io.*;
import java.util.*;
class GFG {

    public static void print2D(int mat[][])
    {
        System.out.println(Arrays.deepToString(mat));
    }

    public static void main(String args[])
        throws IOException
    {
        int mat[][] = { { 1, 2, 3, 4 },
                        { 5, 6, 7, 8 },
                        { 9, 10, 11, 12 } };
        print2D(mat);
    }
}

Output

[[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]

Complexity of the above Method:

Time Complexity: O(N*M)
Auxiliary Space: O(1)