Java – Introduction to Arrays

Array:

• Primitive variable store only one value at a time.
• Array variable can store more than one element of same type.
  • For example  marks[] = {56, 45, 90, 67, 56};
• Array elements store in side by side locations
• Array elements can access using index starts from 0 to length-1;

Array creation:                        

int[]  arr = {3, 7, 1, 9, 5, 2, 7, 6};

Memory representation:

Find the Length of Array:

length:

• ‘length’ variable returns length of array.
• ‘length’ is a pre-defined instance variable.
• ‘length’ variable invokes on array object.

class Code {       public static void main(String[] args)       {                   int[] arr = {4, 2, 8, 9, 1, 6, 7, 4};                   System.out.println(“Length is : ” + arr.length);       } }

Array Object:

• Array is an object in java.
• We can create empty array using ‘new’ keyword.

Creating empty array with specific size as follows

class Code {       public static void main(String[] args)       {                   int[] arr = new int[7];                   System.out.println(“Lengt is : ” + arr.length);       } }

Note:

• If we just declare the array then memory will not be allocated to array.
• We cannot perform any operations of array without memory.
• For example, finding length to array gives error

class Code {       public static void main(String[] args)       {                   int[] arr;                   System.out.println(“Lengt is : ” + arr.length);       } }