Java array and programming example

Q.1  what is an array?

Ø  Array is one type of value containing an array representing a group of elements of the same data type. (homogeneous or similar data type)

Type of array:-

Single dimensional array=  1D array

Multidimensional array = 2-D array/ 3-D  array

Array declaration creation and initialization?

·         Retrieve elements from an array by for and for-each loop.

·         Arrays are object

·         Get a class name for an array

·         What are matrix  and jagged arrays

·         Annonimius array.

·         Array program (sorting, searching, margins, deleting, etc…)

Syntax:--    int   emp_id [] = new int  emp_id[100];

·         Array -   an array is an object that holds a fixed member of values of a homogenous of similar data type

·         Say an array Is a  data  stricter where  we  store similar element 

·         The length of an array is assigned when the array is created and after creations, its length is fixed.

Example:-

int   a [] = new int[10];

It will create an array of length  10 index values we always start from 0(zero).

Feature of an array:-

1.       Java array variables can be declared like other variables with []  after the data type.

2.       The variable  in the array are  ordered  and   each has an  index  beginning  from 0(zero)

3.       In java arrays object and thus they occupy memory in “heap array”.

4.       The direct supper class of an array type of object.

5.       They are  always  created  at runtime

6.       The length of an array can be found by using member length.  This is different from  C /C++  where we find length using the size of.

7.       The elements of an array are stored in consecutive memory locations.      

Advantages of an array:-

1.       Array is used to store multiple data items of some type by using only a single name.

2.       We can access  any element randomly by using index  provided by arrays

3.       Arrays can be used to implement other data structures likeliest, stacks, queues, trees, graphics. etc...

4.       Primitive type  of wrapper   classes  object the connection will not  happen so it  fast

The disadvantage of an array:-

Fixed-size:-   we need to mentation the size of the array thus they have a fixed size .when the array is created size cannot be changed.

Memory wastage:-   there is a  lot of chances  of memory wastage supposes  we create  an array  of length 100 but  only 10 elements are inserted then  90 blocks  are  empty  and thus  memory wastage

Strongly typed:-  array stores only similar data type thus strongly typed.

Reduce performances:-   the elements of an array are stored in a consecutive memory location, thus to declare an element in an array we need to travel throughout the memory so this will reduce performances.

No methods:-     array does not have add or removed method.