How To Print Multi-dimensional Arrays In Java

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In Java, printing an array is a common task. Although, outputting the content of a one-dimensional array is straightforward enough, doing it for the content of a multi-dimensional array is more complex.

To print a multi-dimensional array, you first need to convert its content to a String using nested loops. The code below prints arrays of different dimensions.

class Main { public static void main( String args[] ) { // 1-D array int[] arr = {0, 1, 2, 3, 4}; // 2-D array int[][] matrix = { {0, 1, 2}, {2, 3, 4}, {5, 6, 7} }; // 3-D array int[][][] multiDimArray= { { {0, 1}, {2, 3}, {3, 4} }, { {5, 6}, {7, 8}, {8, 9} } }; System.out.print("1-D Array: \n["); // printing a 1-D array using loop for (int n: arr) { System.out.print(n + " "); // printing each item } System.out.println("]\n"); System.out.print("2-D Array: \n["); // printing a 2-D array using two nested loops for (int[] array: matrix) { System.out.print("["); for (int n: array) { System.out.print(n + " "); // printing each item } System.out.print("]"); // printing new line } System.out.println("]\n"); System.out.println("3-D Array: "); // printing a 3-D array using three nested loops for (int[][] m: multiDimArray) { System.out.print("["); for (int[] a: m) { System.out.print("["); for (int n: a) { System.out.print(n + " "); // printing each item } System.out.print("]"); } System.out.print("]"); } System.out.println("]"); }}Run

We need to use the number of nested loops to iterate on each item of an N-dimensional array before printing it. As the number of dimensions increases, the code becomes more complex and harder to maintain.

However, there is a cleaner approach for this using the Arrays.toString() and Arrays.deepToString() library methods defined within the java.util.Arrays class.

To print a one-dimensional array, you need to call the Arrays.toString() method and pass the array as an argument. However, this only works with one-dimensional arrays.

To print a multi-dimensional array, you instead need to call the Arrays.deepToString() method and pass the multi-dimensional array as an argument.

See the code example below for more clarity on this:

import java.util.Arrays;class Main { public static void main( String args[] ) { // 1-D array int[] arr = {0, 1, 2, 3, 4}; // 2-D array int[][] matrix = {{0, 1, 2}, {2, 3, 4}, {5, 6, 7}}; // 3-D array int[][][] multiDimArray= { { {0, 1}, {2, 3}, {3, 4} }, { {5, 6}, {7, 8}, {8, 9} } }; System.out.println("1-D Array: "); // printing a 1-D array using Arrays.toString System.out.println(Arrays.toString(arr)); System.out.println("\n2-D Array: "); // printing a 2-D array using Arrays.deepToString System.out.println(Arrays.deepToString(matrix)); System.out.println("\n3-D Array: "); // printing a 3-D array using Arrays.deepToString System.out.println(Arrays.deepToString(multiDimArray)); }}Run

Conclusion

You cannot print an array in Java just by using System.out.println(). Instead, you need to loop through each item and convert it to String before printing it.

A cleaner approach would be to use the appropriate utility method from the java.util.Arrays class. To print the content of a one-dimensional array, use the Arrays.toString() method. To print the content of a a multi-dimensional array, use the Arrays.deepToString() method.

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