Print Matrix or 2D array in Java

Print Matrix or 2D array in Java | To print a matrix or 2D array or two-dimensional array, we can use nested loops. It can be either for loop, for-each loop, while loop, or do-while loop. We have another better alternative deepToString() which is given in java.util.Arrays class. First, let us see the Java program using loops.

Java Program to Print Matrix or 2D Array using for loop

public class DisplayMatrix {

  public static void main(String[] args) {
    // declare and initialize a matrix or 2D array
    int matrix[][] = { { 1, 2 }, { 4, 5 }, { 7, 8 } };

    // display matrix using for loops
    // outer loop for row
    for (int i = 0; i < matrix.length; i++) {
      // inner loop for column
      for (int j = 0; j < matrix[0].length; j++) {
        System.out.print(matrix[i][j] + " ");
      }
      System.out.println(); // new line
    }
  }

}

Output:-

1 2
4 5
7 8

In this program matrix.length returns the row size and matrix[0].length returns the size of column. See more:- How to find length of the array in Java.

Print Using For-Each loop

The for-each or inhenced for loop was introduced in Java 1.5 version. Below is the Java program to display a two dimensional array or matrix using for-each loop.

public class DisplayMatrix {

  public static void main(String[] args) {
    // declare and initialize a 3x3 matrix
    int matrix[][] = 
      { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };
    
    // display 2D array using for-each loop
    for(int[] i : matrix) {
      for(int j : i) {
        System.out.print(j + " ");
      }
      System.out.println(); // new line
    }
  }

}

Output:-

1 2 3
4 5 6
7 8 9

Java Program to Print 2D array or Matrix using Arrays.deepToString() method

The java.util.Arrays class in Java contains several methods for basic array problem. It contains toString() method to display one-dimension array and deepToString() method to display the Java multi-dimensional array. Below program uses Arrays.deepToString() method to display the 3×3 matrix.

import java.util.Arrays;

public class DisplayMatrix {

  public static void main(String[] args) {
    // declare and initialize a 3x3 matrix
    int matrix[][] = 
      { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };
    
    // display 2D array using for-each loop
    System.out.println(Arrays.deepToString(matrix)); 
  }

}

Output:-

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

Java Program to take 3×3 matrix elements as input from the user and display it

import java.util.Arrays;
import java.util.Scanner;

public class DisplayMatrix {

  public static void main(String[] args) {
    
    // declare a 3x3 matrix
    int matrix[][] = null ;
    matrix = new int[3][3];
    
    // create Scanner class object to read input
    Scanner scan = new Scanner(System.in);
    
    // read matrix
    System.out.println("Enter 3x3 Matrix elements: ");
    for(int i=0; i<3; i++) {
      for(int j=0; j<3; j++) {
        matrix[i][j] = scan.nextInt();
      }
    }
    
    // display 2D array 
    System.out.println("Entered Matrix: ");
    System.out.println(Arrays.deepToString(matrix)); 
    
    // close Scanner 
    scan.close();
  }

}

Output:-

Enter 3×3 Matrix elements:
10 20 30
40 50 60
70 80 90
Entered Matrix:
[[10, 20, 30], [40, 50, 60], [70, 80, 90]]

In this program, first, we had declared a 3×3 matrix, then we created the Scanner class object to read input values from the end-user. To read input value you can also use the BufferedReader class. The nested for loop is used to read those values. Finally, deepToString() method of the Arrays class is used to display the matrix. Arrays class contains overridden toString() method to display one-dimensional array and deepToString() method to display multi-dimensional array.

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