Determine the Upper Bound of a Two Dimensional Array in Java - GeeksforGeeks

26 Oct, 2020
Multidimensional arrays in Java are common and can be termed as an array of arrays. Data in a two-dimensional array in Java is stored in 2D tabular form. A two-dimensional array is the simplest form of a multidimensional array. A two-dimensional array can be seen as an array of the one-dimensional array for easier understanding. A two-dimensional array is declared with two dimensions that are also referred to as their bounds.  
Syntax of an Array of Arrays:
data_type[][] array_name = new data_type[x][y];

For example: int[][] arr = new int[20][30];    // 20 X 30 array of arrays
Direct Declaration of an Array of Arrays:
data_type[][] array_name = {
{valueR1C1, valueR1C2, ....},
{valueR2C1, valueR2C2, ....}
};

For example: int[][] arr = {{1, 2}, {3, 4}};
Allocation of values in an Array of Arrays
Java
// Allocation of values in an Array of Arraysclass GFG {    public static void main(String[] args)    {          int[][] arr = new int[20][30];        arr[0][0] = 100;          System.out.println("arr[0][0] = " + arr[0][0]);    }}
arr[0][0] = 100
 
Printing complete Array of Arrays
Java
// Printing complete Array of Arraysclass GFG {    public static void main(String[] args)    {          int[][] arr = { { 1, 2 }, { 3, 4 } };          for (int i = 0; i < 2; i++)            for (int j = 0; j < 2; j++)                System.out.println("arr[" + i + "][" + j                                   + "] = " + arr[i][j]);    }}
arr[0][0] = 1
arr[0][1] = 2
arr[1][0] = 3
arr[1][1] = 4
An array of Arrays in java is actually an array of a one-dimensional array. Each row of a two-dimensional array has a length field that holds the number of columns. However, we can get both the row upper bound and the column dimensions using:
int row_bound = array_name.length;
int column_bound = array_name[0].length;

Determine the Dimension of an Array of Arrays
Java
// Determine the Dimension of an Array of Arraysclass GFG {    public static void main(String args[])    {        int[][] arr = new int[10][20];        int row_bound = arr.length;        int column_bound = arr[0].length;        System.out.println("Dimension 1: " + row_bound);        System.out.println("Dimension 2: " + column_bound);    }}
Dimension 1: 10
Dimension 2: 20
 
Note: It is important to understand that Java doesn’t really have two-dimensional arrays. Java arrays are inherently jagged. It has arrays of arrays. So there is no one upper bound/length of the column level.
Example:
Java
// row bound and column boundsclass GFG {    public static void main(String args[])    {        int[][] arr = { { 1, 2 },                        { 3 },                        { 4 },                        { 5, 6, 7, 8 },                        { 9, 10, 11, 12, 13, 14, 15 } };        int row_bound = arr.length;        int column_bound1 = arr[0].length;        int column_bound2 = arr[1].length;        int column_bound5 = arr[4].length;        System.out.println("Dimension 1: " + row_bound);        System.out.println("Dimension 2: " + column_bound1);        System.out.println("Dimension 3: " + column_bound2);        System.out.println("Dimension 4: " + column_bound5);    }}
Dimension 1: 5
Dimension 2: 2
Dimension 3: 1
Dimension 4: 7
Java-Array-Programs
Java-Arrays
Java
Java Programs
Java
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
Stream In Java
Different ways of Reading a text file in Java
Constructors in Java
Exceptions in Java
Generics in Java
Convert a String to Character array in Java
Java Programming Examples
Convert Double to Integer in Java
Implementing a Linked List in Java using Class
How to Iterate HashMap in Java?