How to iterate over a two dimensional array in Java?

In this post, I am going to explain how to loop over a two dimensional array.

 

What is a multi-dimensional array?

Multidimensional arrays are the arrays of arrays.

 

Syntax to create two dimensional Array

dataType arrayName[][] = new dataType[size1][size2]

         (OR)

dataType[][] arrayName;

arrayName = new dataType[size1][size2]

 

 Example

 int arr[][] = new int[3][4];

 

Above snippet creates a 3 * 4 array, where array has 3 rows and 4 columns.

 

 

As shown in the above image,

a.   0^th row and  3^rd column has value 4 and it can be accessed with index notation like arr[0][3].

b.   2^nd row and 1^st column has value 10 and it can be access with index notation like arr[2][1].

 

Let’s see below examples to print two dimensional array content using for, while and do-while loops.

 

Using two for loops

for(int row = 0; row < noOfRows; row++) {
	for(int column = 0; column < arr[row].length; column++) {
		System.out.printf("arr[%d][%d] = %d\n", row, column, arr[row][column]);
	}
	System.out.println();
}

ArrayTraversalUsingForLoop.java

package com.sample.app;

public class ArrayTraversalUsingForLoop {

	public static void main(String[] args) {
		final int arr[][] = {
				{2, 3, 5, 7},
				{11, 13, 17},
				{19, 23, 29, 31, 37, 41}
		};
		
		final int noOfRows = arr.length;
		
		for(int row = 0; row < noOfRows; row++) {
			for(int column = 0; column < arr[row].length; column++) {
				System.out.printf("arr[%d][%d] = %d\n", row, column, arr[row][column]);
			}
			System.out.println();
		}
	}

}

Output

arr[0][0] = 2
arr[0][1] = 3
arr[0][2] = 5
arr[0][3] = 7

arr[1][0] = 11
arr[1][1] = 13
arr[1][2] = 17

arr[2][0] = 19
arr[2][1] = 23
arr[2][2] = 29
arr[2][3] = 31
arr[2][4] = 37
arr[2][5] = 41

Using while loops

final int noOfRows = arr.length;

int row = 0;
while(row < noOfRows) {
	int column = 0;
	
	while(column < arr[row].length) {
		System.out.printf("arr[%d][%d] = %d\n", row, column, arr[row][column]);
		column++;
	}
	
	row++;
	System.out.println();
}

ArrayTraversalUsingWhileLoop.java

package com.sample.app;

public class ArrayTraversalUsingWhileLoop {

	public static void main(String[] args) {
		final int arr[][] = {
				{2, 3, 5, 7},
				{11, 13, 17},
				{19, 23, 29, 31, 37, 41}
		};
		
		final int noOfRows = arr.length;
		
		int row = 0;
		while(row < noOfRows) {
			int column = 0;
			
			while(column < arr[row].length) {
				System.out.printf("arr[%d][%d] = %d\n", row, column, arr[row][column]);
				column++;
			}
			
			row++;
			System.out.println();
		}
	}

}

Array traversal using do-while loop

ArrayTraversalUsingDoWhileLoop.java

package com.sample.app;

public class ArrayTraversalUsingDoWhileLoop {

	public static void main(String[] args) {
		final int arr[][] = {
				{2, 3, 5, 7},
				{11, 13, 17},
				{19, 23, 29, 31, 37, 41}
		};
		
		final int noOfRows = arr.length;
		
		int row = 0;
		do {
			int column = 0;
			
			do {
				System.out.printf("arr[%d][%d] = %d\n", row, column, arr[row][column]);
				column++;
			}while(column < arr[row].length);
			
			row++;
			System.out.println();
		}while(row < noOfRows);
	}

}

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