Java Multi-Dimensional Arrays
Last Updated :
23 Apr, 2025
Multidimensional arrays are used to store the data in rows and columns, where each row can represent another individual array are multidimensional array. It is also known as array of arrays. The multidimensional array has more than one dimension, where each row is stored in the heap independently. This allows us to make rows of different sizes. Which is more flexible than the one-dimensional tabular arrays.
Example: This Java program shows how to create and use a multidimensional array.
Java
// Java Program to Demonstrate
// Multi Dimensional Array
import java.io.*;
public class Geeks
{
public static void main(String[] args){
// Multidimensional array declaration
int[][] arr;
// Initializing the size of row and column respectively
arr = new int[1][3];
// Initializing the values
arr[0][0] = 3;
arr[0][1] = 5;
arr[0][2] = 7;
// Display the values using index
System.out.println("arr[0][0] = " + arr[0][0]);
System.out.println("arr[0][1] = " + arr[0][1]);
System.out.println("arr[0][2] = " + arr[0][2]);
}
}
Outputarr[0][0] = 3
arr[0][1] = 5
arr[0][2] = 7
Syntax for Multi-Dimensional Array
data_type[1st dimension][2nd dimension][]..[Nth dimension] array_name = new data_type[size1][size2]....[sizeN];
Parameters:
- data_type: Type of data to be stored in the array. For example: int, char, etc.
- dimension: The dimension of the array created. For example: 1D, 2D, etc.
- array_name: Name of the array
- size1, size2, ..., sizeN: Sizes of the dimensions respectively.
Examples:
// Two dimensional array:
int[][] arr2d = new int[3][5];
// Three dimensional array:
int[][][] arr3d = new int[3][5][7];
Size of Multidimensional Arrays: The size of the multidimensional array can be calculated by multiplying the size of all dimensions of array foe example arrd have the dimensions 3*5 = 15
For example: array int[][][] x = new int[3][5][7] can store a total of (3*5*7) = 105 elements.
Two-Dimensional Array (2D-Array)
Two-dimensional array is the simplest form of a multidimensional array. A 2-D array can be seen as an array storing multiple 1-D array for easier understanding.
Syntax (Declare, Initialize and Assigning)
// Declaring and Intializing
data_type[][] array_name = new data_type[x][y];
// Assigning Value
array_name[row_index][column_index] = value;
A 2-D array can be seen as a table with 'x' rows and 'y' columns where the row number ranges from 0 to (x-1) and column number ranges from 0 to (y-1). A 2-D array 'x' with 3 rows and 3 columns is shown below:
Example 1: We can add the values directly to the array while declaring the array.
Java
// Java Program to demonstrate the use of
// Two Dimensional Array
import java.io.*;
class Main {
public static void main(String[] args){
// Array Intialised and Assigned
int[][] arr = { { 1, 2 }, { 3, 4 } };
// Printing the Array
for (int i = 0; i < 2; i++){
for (int j = 0; j < 2; j++)
System.out.print(arr[i][j]+" ");
System.out.println();
}
}
}
Example 2: Updating the values while executing works both ways can be accepted by user or by some variable.
Java
// Java Program to demonstrate the use of
// Two Dimensional Array
public class Geeks
{
public static void main(String[] args) {
// Row and Columns in Array
int n = 2;
int m = 2;
// Array declared and initialized
int[][] arr = new int[n][m];
int it = 1;
// Assigning the values to array
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
arr[i][j] = it;
it++;
}
}
// Printing the Array
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++)
System.out.print(arr[i][j] + " ");
System.out.println();
}
}
}
Accessing Elements of Two-Dimensional Arrays
In Two dimensional array the the row is present by the i and the column is present by the j and we can get the element using arr[i][j] using the nested loop. arr is the name of the variable which reference to the two dimensional array.
Note: In an array of size N, indices range from 0 to N-1. Thus, row index 2 corresponds to the actual row number 3.
Example: Accessing the elements of 2D array using indexes.
Java
// Java Program to demonstrate Accessing
// Elements of Two-Dimensional Arrays
import java.io.*;
class Main {
public static void main(String[] args){
int[][] arr = { { 1, 2 },
{ 3, 4 } };
// Accessing Element at index
// row=1 and column=1
System.out.println("a[1][1] : " + arr[1][1]);
}
}
Follow the Steps mentioned below to create a Two Dimensional Array with User input:
- First import the Scanner class from the util pcakage at top of the program.
- Then create a Scanner class object. Then give a promt to user to enter the size of row and column.
- Then create a nested loop to take input from user to add element in the multi-dimensional array.
- Then print the multi-dimensional array and close the scanner object.
Example: Java program to demonstrate how to create Two Dimensional Array with User input.
Java
// Java Program for Creating two
// Dimensional array with user Inputs
import java.util.Scanner;
public class Geeks
{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
// Taking Number of Rows and Columns from User
System.out.print("Enter number of rows: ");
int row = sc.nextInt();
System.out.print("Enter number of columns: ");
int col = sc.nextInt();
int[][] arr= new int[row][col];
System.out.println("Enter elements of array: ");
// Taking input from user for each element of array
// using nested for loop
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++) {
arr[i][j]= sc.nextInt();
}
}
System.out.println("Elements of array are: ");
// Printing Elements of Arrays
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++) {
System.out.print(arr[i][j]+ " ");
}
System.out.println();
}
sc.close();
}
}
Output:
Three - Dimensional Array (3D-Array)
3D-Array is a complex form of a multidimensional array. A 3D-array can be seen as an array of 2D array for easier understanding.
A three-dimensional array can be seen as a table of arrays with 'x' rows and 'y' columns where the row number ranges from 0 to (x-1) and column number ranges from 0 to (y-1). A three - dimensional array with 3 array containing 3 rows and 3 columns is shown below:
Example 1: Java program to show how to create and print 3D array.
Java
// Java Program to Demonstrate
// Three Dimensional Array
import java.io.*;
class Geeks
{
public static void main(String[] args){
// Array Created and Initialized
int[][][] arr = { { { 1, 2 }, { 3, 4 } }, { { 5, 6 }, { 7, 8 } } };
// Defining the x,y,z in Multi
// Dimensional Array
int n = arr.length;
int m = arr[0].length;
int o = arr[0][0].length;
// Printing the Array
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
for (int k = 0; k < o; k++) {
System.out.println("arr[" + i + "][" + j + "][" + k + "] = " + arr[i][j][k]);
}
}
}
}
}
Outputarr[0][0][0] = 1
arr[0][0][1] = 2
arr[0][1][0] = 3
arr[0][1][1] = 4
arr[1][0][0] = 5
arr[1][0][1] = 6
arr[1][1][0] = 7
arr[1][1][1] = 8
Example 2: Java program to assigning the values in 3D array using indexes.
Java
// Java Program to Implement
// Three Dimensional Array
import java.io.*;
class Main {
public static void main(String[] args){
int[][][] arr = new int[2][2][2];
// Three Dimensional x,y,z dimension
int n=arr.length;
int m=arr[0].length;
int o=arr[0][0].length;
int it=1;
// Assigning the values to array
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
for(int k=0; k < o; k++){
arr[i][j][k] = it;
it++;
}
}
}
// Printing the Array
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++){
for(int k=0; k < o; k++)
System.out.print(arr[i][j][k] + " ");
System.out.println();
}
System.out.println();
}
}
}
Accessing Elements of Three-Dimensional Arrays
Elements in three-dimensional arrays are commonly referred by x[i][j][k] where 'i' is the array number, 'j' is the row number and 'k' is the column number.
Note: In arrays if size of array is N. Its index will be from 0 to N-1. Therefore, for row_index 2, actual row number is 2+1 = 3.
Example: Accessing the elements of 3D array using indexes.
Java
// Java Program to Demonstrate Accessing
// Three Dimensional Array by Index
import java.io.*;
class Geeks
{
public static void main(String[] args){
// Creating an Array
int[][][] arr = { { { 1, 2 }, { 3, 4 } },
{ { 5, 6 }, { 7, 8 } } };
// Printing array at index 0 , 0 , 0
System.out.println("arr[0][0][0] = " + arr[0][0][0]);
}
}
Inserting a Multi-Dimensional Array During Runtime
Now we can insert a multidimensional array at runtime here we are going to use the Scanner class and then we take the element of the multidimensional array from the user and then we print the count of the even and odd element which user give as an input.
Example: Taking a input from user of mutidimensional array (Runtime) and print the count of even and odd number given by user.
Java
// Java Program Demonstrating use of
// Multi Dimensional Array
import java.io.*;
import java.util.Scanner;
class Geeks {
public static void main(String[] args)
{
Scanner s = new Scanner(System.in);
// Number of rows
int n = s.nextInt();
// Initialize a 2D array
int[][] arr = new int[n][];
int t = 0;
// Input for each row
for (int i = 0; i < n; i++) {
int m = s.nextInt();
// Assuming all rows have the same column count
t = m;
arr[i] = new int[m];
for (int j = 0; j < m; j++) {
arr[i][j] = s.nextInt();
}
}
int odd = 0, even = 0;
System.out.println("Rows " + n + " with " + t
+ " Columns");
System.out.println("Elements of Array:");
// Print the entire array and count even/odd numbers
for (int i = 0; i < n; i++) {
for (int j = 0; j < arr[i].length; j++) {
System.out.print(arr[i][j] + " ");
// Count even and odd numbers
if (arr[i][j] % 2 == 0) {
even++;
}
else {
odd++;
}
}
System.out.println();
}
// Print the aggregated results
System.out.println("Even: " + even
+ ", Odd: " + odd);
s.close();
}
}
Application of Multi-Dimensional Array
- Multidimensional arrays used to arrange the data in more managable form ( Tabular form ) for example arranging the data of a student such as student roll no and marks and The image representation in 3D matrix.
- In dynamic programming questions, multidimensional arrays are used which are used to represent the states of the problem.
- Apart from these, they also have applications in many standard algorithmic problems like: Matrix Multiplication, Adjacency matrix representation in graphs, Grid search problems.
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