Java Multidimensional Array

Array can be multidimensional as matrix like. When you want to store data as a tabular form like rows and columns in a table we can use multidimensional array.

Syntax:

type [] [] array_name ={ {elements}, {elements} };

Like: 

int [][] numbers = { {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10} };

Note: Here, if we want to access the first {} array data, then we have to use index [0], 2nd array {} data, we have to use index [1] and use specific index number to access the elements of that array. Here, first [] brackets indicates the undex number and the second [] brackets specify the element of that index.

# Create a multidimensional array and access elements

Example 1:

public class Main{
  public static void main (String[] args) {
    //create a multidimensional array
    int [] [] numbers = { {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10} };
    
    //access the first array elements
    System.out.println("First array element is "+numbers[0] [2]);
    
    //access the second array elements
    System.out.println("Second array element is "+numbers[1] [4]);
  }
}
/**
 * Output: 
 * First array element is 3
 * Second array element is 10
 */

We know that, array index starts with [0]. First array is [0], second array is [1], and third array is [2] and so on.

If we want to access the first array elements, we have to use 2 square brackets like numbers [] []. One for the array and another one for the elements of that array.

So, if we want second array element like 10 then the syntax should be like this:
numbers [1][4]; //output: 10

# Change the array elements of multidimensional array

Like a one dimensional array, you can change the array elements of multidimensional array too.

public class Main{
  public static void main (String[] args) {
    //create a multidimensional array
    int [] [] numbers = { {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10} };
    
    //access the first array elements
    System.out.println("Second element of the first array is: "+numbers[0] [2]);
    
    //Change the first array elements
    numbers[0][2] = 20;
    
    System.out.println("Now the second element of first array is "+numbers[0][2]);
  }
}
/**
 * Output: 
 * Second element of the first array is 3
 * Now the Second element of first array is 20
 */
 

You can see, how we have changed the second element of the first array.

# Loop through multidimensional array

Using for loop:

public class Main{
   public static void main (String[] args) {
     //create a multidimensional array
     int [] [] numbers = { {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10} };
     
     //loop through the numbers array
     // using nested for loop
     //one for index, another one for elements of that index
     
     for(int i = 0; i < numbers.length; i++){
       for(int j = 0; j < numbers[i].length; j++){
         System.out.println(numbers [i] [j]);
       }
     }
      
   }
 }

/**
 * Output: 
 * 1
 * 2
 * 3
 * 4
 * 5
 * 6
 * 7
 * 8
 * 9
 * 10
 */

# Array iteration using for each loop:

public class Main{
   public static void main (String[] args) {
     //create a multidimensional array
     int [] [] numbers = { {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10} };
     
     //loop through array elements
     for(int[] arrays : numbers){ //array
       for(int data: arrays){ //elements of that array
         System.out.println(data);
       }
     }
      
   }
 }

/**
 * Output: 
 * 1
 * 2
 * 3
 * 4
 * 5
 * 6
 * 7
 * 8
 * 9
 * 10
 */

Okay. The above one is, simplest form of 2 dimensional array. So, how to create 3, 4 or 5 dimensional arrays?

Not very difficult at all.

Syntax will be for n (2, 3, 4, 5...) dimensional arrays are:

type n[] array_name = n{};

like for 3 dimensional array:

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

Like for 4 dimensional array: int [] [] [] [] myArray = {{{ {1, 2, 3, 4}, {5, 6, 7, 8} }}};

Hope this this makes sense.

Now the question is, How to loop through 3 or 4 dimensional arrays? Similarly the 2 dimensional array. You have to use 1 more for loop always.

Look at the below 3 dimensional array and how we loop it through. (Using for each loop)

public class Main{
   public static void main (String[] args) {
     int [] [] [] numbers = {{ {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10} }};
     
     //loop through the numbers array
     for(int [] [] arrays: numbers ){
       for(int [] values: arrays){
         for(int data: values){
           System.out.println(data);
         }
       }
     }
   }
 }
 
/**
 * Output:
 * 1
 * 2
 * 3
 * 4
 * 5
 * 6
 * 7
 * 8
 * 9
 * 10
 */