
Array is a Non-Primitive Data for Java. Java’s array contains many elements of the same data type. But these elements are in their nearby memory locations.
Java Array keeps these variables of primitive data types inside.
Array is an object. Which holds the same primitive data type variables. Array’s size is fixed.
Length of Array is 5 | |||||
Array_Elements | |||||
Array_index | 0 | 1 | 2 | 3 | 4 |
Array has three methods.
- Array Declaration
- Creating Array
- Array Initialization
Syntax for Array Declaration
The declaration of Array is done in two ways.
data_type array_name []; // or
data_type [] array_name;
The first type in Syntax is the one used for java.
There is another type in Syntax which is used in C and C ++. It also works in java, but is not used.
Example for Array Declaration
When declaring an Array, its size is not given in its subscript ([]).
int [] arr;
char [] str;
double [] arr;
Syntax for Creating Array
data_type [] array_name = new data_type [array_size]; // declaring and creating Array
Example for Creating Array
The new operator is used when Array is to be created. Here the size of the array is given.
In the following example, two types of array named ‘arr’ are declare and create.
In the first type ‘arr’ this array has also been created with declaration.
In another type, ‘arr’ has declared this array first and subsequently it has been created.
int [] arr = new int [10]; // declaring and creating Array
// or
int [] arr; // declaring array
arr = new int [10]; // Creating Array
Length of Array is 10 | ||||||||||
Array_Elements | ||||||||||
Array_index | arr [0] | arr [1] | arr [2] | arr [3] | arr [4] | arr [5] | arr [6] | arr [7] | arr [8] | arr [9] |
Array name is ‘arr’ |
Syntax for Array Initialization
data_type [] array_name = {array_elements};
Here the array is initialized in a single line. The initialization of this array does not require a new operator. As values are given in elements. As such, the size of the array also increases.
Example for Array Initialization
int [] arr = {1, 2, 3, 4, 5};
Here the array is initialized seperatly.
Example for Array Initialization
arr [0] = 1; // Array initialization index by index
arr [1] = 2;
arr [2] = 3;
arr [3] = 4;
arr [4] = 5;
Accessing Array Elements
Array’s elements are accessed in two ways.
- By indexing
- By for or for each loop
1. By Indexing: Accessing Array Elements
For Example, Source Code:
class Sample {
public static void main (String args []) {
int [] arr = {1, 2, 3, 4, 5}; // Array initialization
System.out.println ("arr [0] =" + arr [0]);
System.out.println ("arr [1] =" + arr [1]);
System.out.println ("arr [2] =" + arr [2]);
System.out.println ("arr [3] =" + arr [3]);
System.out.println ("arr [4] =" + arr [4]);
}
}
Output:
arr [0] = 1
arr [1] = 2
arr [2] = 3
arr [3] = 4
arr [4] = 5
1. By for or for each Loop: Accessing Array Elements
Using For Loop
For Example,
Source Code:
class Sample {
public static void main (String args []) {
int [] arr = {1, 2, 3, 4, 5}; // Array initialization
int i;
for (i = 0; i
Output :
arr [0] = 1
arr [1] = 2
arr [2] = 3
arr [3] = 4
arr [4] = 5
Using For each Loop
For Example,
Source Code:
class Sample {
public static void main (String args []) {
int [] arr = {1, 2, 3, 4, 5};
for (int i: arr) {
System.out.println ("arr [" + (i-1) + "] =" + i);
}
}
}
Output:
arr [0] = 1
arr [1] = 2
arr [2] = 3
arr [3] = 4
arr [4] = 5
Java - Types of Array
There are two types of array.
- One-dimensional dimensions
- Two-Dimensional or Multi-Dimensional Array
1. One-Dimensional Array
Array Declaration, Creating Array, Array Initialization and Accessing Array on Array Introductions are all of ‘One Dimensional Array’. You can read it.
2. Two-Dimensional or Multi-Dimensional Array
Multi-Dimensional Array Declaration
int arr [] []; // or
int [] [] arr; // or
int [] arr [];
Create Multi-Dimensional Array
int arr [] [] = new int [2] [2]; // or
int [] [] arr = new int [2] [2]; // or
int [] arr [] = new int [2] [2];
Multi-Dimensional Array Initialization
int arr [] [] = {{1, 2}, {3, 4}};
Elements of Multi-Dimensional Array are accessed in two ways.
- By indexing
- By for loop
1. By Indexing: Accessing Array Elements
For Example, Source Code:
class Sample {
public static void main (String args []) {
int [] [] arr = {{1, 2}, {3, 4}}; // Array initialization
System.out.println ("arr [0] [0] =" + arr [0] [0]);
System.out.println ("arr [0] [1] =" + arr [0] [1]);
System.out.println ("arr [1] [0] =" + arr [1] [0]);
System.out.println ("arr [1] [1] =" + arr [1] [1]);
}
}
Output:
arr [0] [0] = 1
arr [0] [1] = 2
arr [1] [0] = 3
arr [1] [1] = 4
1. By for Loop: Accessing Array Elements Using For Loop
For Example,
Source Code:
class Sample {
public static void main (String args []) {
int [] [] arr = {{1, 2}, {3, 4}}; // Array initialization
int i, j;
for (i = 0; i
Output :
arr [0] [0] = 1
arr [0] [1] = 2
arr [1] [0] = 3
arr [1] [1] = 4