Sunday 30 June 2013

DATA TYPES IN JAVA




DEFINITION :

Data type in any language is the type of data that is used to represent the values such as the whole numbers(Integer types) , number with decimal points(floating point), characters etc.
Data type in java language is one of the most fundamental element.
There are two types of data in Java, these are :
1. Primitive type
2. Reference type


PRIMITIVE TYPE :

The primitive type is simple type which represent only single value - not complex objects. The reason for this is the performance. Since if we make simple type as the object than it must contain some property and some behaviour which will result in degraded performance.
They are used for reffering only a single value or we can say that they are not like the actual objects(which has a property and behaviour).


Four types of Primitive data type are :
1. INTEGERS :  byte, short, int, and long - data types in Integers group.
2. FLOATING-POINT NUMBERS : float and double - data types in Floating point group.
3. CHARACTERS : char - data type in the characters group.
4. BOOLEAN : boolean - data type in the boolean group.


Now in java all the data types have a strictly defined range to make it portable. For example, an int is always 32 bits, regardless of the particular platform. However the size can be changed later by Java Runtime Environment which depends upon the processor of your computer.

INTEGERS :
There are four integer types that java supports :
1. byte : 
It is the smallest integer type.
width : 8 bits, range : -128 to +127.
Use : The variables of type "byte" are especially useful when you're working with a stream of data from a network or file.
declaration : declared with byte keyword.
e.g,
byte b;

2. short :
It is probably the least used java type.
width : 16 bits, range : -32,768 to +32,767
Use : Used mostly in 16 bit computers or we can say that 16 bit microprocessors.
declaration : declared with short keyword.
e.g,
short s;

3. int :
It is the most commonly used integer data type.
width : 32 bits, range : -2,147,483,648 to +2.147.483.647
Use : Mostly used in control loops and to index arrays.
declaration : declared with int keyword.
e.g,
int a;

4. long :
It is largest integer type.
width : 64 bits, range : -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807
Use : It is useful when big whole numbers are needed like in the calculation of large distances. for e.g, in measuring the distance of earth from the sun.
declaration : declared with long keyword.
e.g,
long g;

Note : All of the above integer types are signed, positive and negative values. Java does not support unsigned, positive only integers.

FLOATING POINT TYPES :
The floating point numbers are also known as the real numbers and are used when evaluating expressions that require fractional precision.
There are two kinds of floating point types :
1. float :
It specifies a "single precision" value or we can say it specifies  the small decimal value as compared with the double.
width : 32 bits, range : 1.4e-045 to 3.4e+038
Use : Mostly used in representing dollers and cents.
declaration : declared with the help of float keyword.
e.g,
float doller;

2. double :
It specifies a "double precision" value. It is actually faster than single precision on some modern processors that have been optimized for high-speed mathematical calculations.
width : 64 bits, range : -4.9e-324 to 1.8e+308
Use : All transcendental math functions, such as sin(), cos(), and sqrt(), return double values.
declaration : declared with the use of double keyword.
e.g,
double pi = 3.1416;

CHARACTERS :
The data type used to represent characters is char.
char :
It represents characters ASCII value.
width : 16 bits, range : 0 to 65,536
The width of char data type is 16 bits because it is represented by "Unicode" which is the combination of all the characters of different languages in the world, such as Latin, Greek, Arabic, English etc.
Also there are no negative chars.
Use : used to represent characters.
declaration : declared with the use of char keyword.
e.g,
char a = 'Y';

BOOLEANS :
The data type used to represent booleans is boolean.
It can have only one of the two possible values, true or false.
The default value of boolean is false.
Use : Mostly used in the conditional expressions that govern the control statements such as if and for.
e.g,
boolean b = true;

Note : It should not be assumed as a string which is different that boolean.


REFERENCE TYPES :

As the name, reference data types are used to refer to a particular object.
for e.g,
My_Class reference = new My_Class();
Here, reference is the reference variable which is used to refer to a My_Class object.

The reference variables are created in the heap. They can be of Array type or any class type.


Java is a strongly typed language because in java every variable has a type, every expression has a type and every type is strictly defined.

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Saturday 15 June 2013

ME AND MY WECHAT GROUP



     This is the post for the WeChat (the best mobile messanger app) Contest.

The five people I would like to connect with in WeChat are :


1. James Arthur Gosling : He is known as the   

father of java programming language. He created the original design of java and implemented the language's original compiler and virtual machine. I want to connect with him because he is my inspiration. I want to thank him for his wonderful effort in the technology. He is one of the legend who changes the way we think about technology.


2. Sachin Tendulkar : He is little master who
     is the greatest batsman in one day International Cricket and second only to Don Bradman in the all time greatest list in test cricket. I want to connect with him because i am a lover of cricket. I want to learn cricket from him. I want some cricket tips from him.



3. Albert Einstein :  He is the father of physics. Its 
major contribution in physics was the general theory of relativity and develop an energy-mass relation with his formula E=mc2. He is also nobel price winner in 1921. I want to connect with him because of his qualities. He is a great man.




4. Chetan Bhagat : He is an Indian writer who write 

novals. One of  his famous noval "Three mistakes of my life" is my favourite noval. I want to connect with him because he inspired me alot from his novals. He is one of the greatest writers in Indian history. 



Here's my chat with Chetan :
Me : Hey, Chetan. Please write something about me on your next book.
Chetan : Ya sure.. but how can i know about you.?
Me : I will tell you with video calling in WeChat.
Chetan : okay.. Wait for it, i will send you request when i will free.
Me : okay.. Thanks.. It was nice talking to you. :)


5. Supi(fictitious) :  He will break the record of 

Sachin Tendulkar, use more brain than Einstein and write novals. He will make a new programming language. I just want to connect with him because I don't want to miss a chance to connect with the future of all the legends.



Here's some part of my group chat with Einstein and Supi :
Me : Supi(fictitious), How could you do that ?
Supi : It was just an easy job for me.. :D
Me : Hahaha.. You are second Rajnikanth in the world.. :P
Supi : Thanks for your compliment. :)
Me : Einstein, You are gone now. No one will remember you in the future, Its all about Supi. :P
Einstein : ohh... Not know what to do.. :(


About WeChat :



WeChat is a mobile text and messaging communication service developed by Tencent in China. It was first released in January, 2011. It is a mobile messanger app in which voice chatting, group chatting and many more features. Now the time it ranked at number one in the world as compared to other messanger apps.

WeChat you tube channel tells you more about WeChat.

Here are some features that WeChat provides :

1. Free : Most messanger apps in the market are not free. They take charges for use but WeChat is free app.



2. Group and Live Chat : We chat provides you to connect with as many people as you want in a group chat.



3. Connect With Facebook : WeChat gives you the option so that you can connect with facebook friends with just single click.





4. Save Chat History/Backup : Saves your chat history in another file with password.


5. Video Call : Provides you the option of video calling in which you can talk with other person face to face.


6. Voice Chat : You can chat by your voice at anytime between the live chat also.


7. Web WeChat : Chat by the use of your pc.


8. Moments : Share your pics with your friends and public also.


9. Emoticons : Emoticons are the way to express your mood. Select one of the image from different images and share it.


10. Platforms : Supports almost all the platforms.


Hope these features are enough to convince you for WeChat.

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