Java Arrays

An array is a group of similar or related data items which is having same name for all elements.

Problems of without using array

Array is useful when we want to store elements of same type without wasting of memery. Without array it results in following frustration to programmer.

• Need to declare number of variables when datatype is same.
  Ex- if we want to take 5 integers for accepting marks then it will be created as int m1,m2,m3,m4,m5 which increases length of the program.
• For assigning values to above variables we need to remember their names everytime.
• More statements are required to perform operations on these variables.

Need of Array in Program

Array is required to overcome above problems and increase the effiency of the program

• Array can handle many number of elements using only single name.
• Array stores multiple values in a variable of same type.
• Array allows us to esily retrive or store elements
• Array allocates the contigues memory space for storing elements
• Array can store elements of specified size not more than it.

Types of arrays

1. One Dimensional Array
2. Two Dimensional Array / Multi Dimensional Array

One Dimensional Array

An array with single subscript is called as One Dimensional Array.

Syntax

Declaration

type arrayName [];
or 
type [] arrayName;

Creating an Array

arrayName = new type [size];

We can also create both of the statements into single statement.

Creation and Declaration in one statement

type arrayName [] = new type [size];

Example

class ArrayDemo 
{
    public static void main(String args[])
    {
	int Array[] = new int[6];
    }
}

Assigning value to Array

Storing values to array is known as initialization of arrays. Java creates array starting with subscript 0 as first index and store the values till arraySize - 1.

There are two methods to assign value

1. Initializing array using subscript

class OneDimen 
{
    public static void main(String args[])
    {
	int Array[] = new int[6];
		
	Array[0] = 10;
	Array[1] = 15;
	Array[2] = 32;
	Array[3] = 47;
	Array[4] = 59;
	Array[5] = 22;
    }
}

2. Initializing at the time of declaration

class ArrayDimen 
{
    public static void main(String args[])
    {
	int Array[] = {10,15,32,47,59,22};
    }
}

Storing of Array into Memory

Array elements are always stored from starting index 0 and ends at arraySize - 1.

here in example element 10 is stored at location Array[0] and ended with location 5