Array in Java
20:07:00
Array in java
Array is a collection of
similar type of data. It is fixed in size that means you can't increase the
size of array at run time. It is collection of homogeneous data elements. It
store the value on the basis of index value.
Advantage of Array
One variable can store multiple value: The main advantage of array is we can represent
multiple value under the same name.
Code Optimization: No, need to declare a lot of variable of same type data, We can
retrieve and short data easily.
Random access: We can retrieve any data from array with the help of index value.
Disadvantage of Array
The main limitation of array is Size Limit when
once we declare array there is no chance to increase and decrease the size of
array according to our requirement, Hence memory point of view array concept is
not recommended to use. To over come this limitation in java introduce
collection concept.
Types of Array
There
are two types of array in java.
·
Single Dimensional Array
·
Multidimensional Array
Array Declaration
Single
dimension array declaration.
1. int[] a;
2. int a[];
3. int []a;
|
Note: At the time of array declaration we can
not specify the size of array. For Example int[5] a; this is wrong.
2D Array declaration.
1. int[][] a;
2. int a[][];
3. int [][]a;
4. int[] a[];
5. int[] []a;
6. int []a[];
|
Array creation
Every array in a java is an object, Hence we can create array by
using new keyword.
int[] arr = new int[10]; // The size of array is 10.
or
int[] arr = {10,20,30,40,50};
|
Accessing array elements
Access
the elements of array by using index value of an elements.
arrayname[n-1];
|
Access Array Elements
int[] arr={10,20,30,40};
System.out.println("Element at 4th place"+arr[2]);
|
Example of Array
public class ArrayEx
{
public static void main(String []args)
{
int arr[] = {10,20,30};
for (int i=0; i < arr.length; i++)
{
System.out.println(arr[i]);
}
}
}
|
Output
10
20
39
|
Note:
1) At the time of array creation we must be specify the size of
array otherwise get an compile time error. For Example
int[] a=new int[]; Invalid.
int[] a=new int[5]; Valid
int[] a=new int[]; Invalid.
int[] a=new int[5]; Valid
2)
If we specify array size as negative int value, then we will get run-time error,
NegativeArraySizeException.
3)
To specify array size the allowed data types are byte, short, int, char If we
use other data type then we will get an Compile time error.
4)
The maximum allowed size of array in java is 2147483647 (It is maximum value of
int data type)
Difference Between
Length and Length() in Java
length: It
is a final variable and only applicable for array. It represent size of array.
Example:
int[] a=new int[10];
System.out.println(a.length); // 10
System.out.println(a.length()); // Compile time error
|
length(): It is final method applicable only for String objects. It represent number
of character present in String.
String s="Java";
System.out.println(s.length()); // 4
System.out.println(s.length); // Compile time error
|
Note: Array is presently not used in Java due to limitations, You need not waste too much time in this area, Consecrate in Java Collections.
0 comments