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Datatypes in Java-


Datatypes in Java-

In java every variable has a type, every expression has a type and all types are strictly defined. All the assignments should be checked by the compiler for the type compatibility. Hence java language considers as strongly typed language. Java is not considered as pure object oriented programming language because several OOP features(like multiple inheritance, operator overloading) are not supported by java. Even java contains non-object primitive datatypes .

Except boolean and char all the remaining datatypes are signed datatypes i.e we can represent both +ve and –ve numbers. 

byte  ---

Size : 8-bits  

Range: -128 to 127 

-ve numbers can represented in 2’s compliment form.  

byte b = 10; 
byte b = 127; 
byte b = 130; C.E: possible loss of precision 

byte b = true;  C.E: Incompatible types found: boolean        required: byte  byte datatype is best suitable if we are handling data either from file or form network.    

short --- 

 size = 2 bytes   

range = -215 to 215 -1 (-32768 to 32767)      

Ex:    short s = 10; 

short s = 32767; 

short s = 65535; C.E: possible loss of precision. 

short s = true;   C.E: Incompatible types short is best suitable datatype for 16-bit process. But currently these are completely out dated and hence the corresponding datatypes also no one is using. 

int ----

 The most commonly used datatype is int.  

size =  4 bytes 

range = -231 to 231 – 1(-2147483648 to 2147483747)

 The size of int is always fixed irrespective of platform hence the chance of failing java program is very less if u r changing the platform hence the java is considered as Robust. 

long ---

if int is not enough to hold big values then we should go for long-

size = 8 bytes  

range = -263 to 263 – 1  

Ex:   The amount of distance traveled by light in 1000days can be represented by long datatype only and int is not enough. 

floating-point ---

for representing real numbers(numbers with decimal points) 

floating –point datatypes divided into two types

float and double 


size = 4 bytes 

range = -3.4e38 to 3.4e38 

If 6 to 7 decimal places of accuracy required 

Considered as single precision 


Size=8 bytes
range = -1.7e308 to 1.7e308 

If 14 to 15 decimal places of accuracy required 

Considered as double precision

boolean datatye  

size = not applicable(virtual machine dependent).

 range = not applicable but allowed values are true/false. 
 Which of the following boolean declarations are valid   

boolean b1 = true;  (Right)
boolean b2 = 0;  (Wrong)  Incompatible types found:int required : boolean boolean b3 = TRUE;(wrong)capital TRUE is not valid

Ex:  int x = 0; 
if(x) { 
System.out.println("Hello"); } 

else {  

 System.out.println("Hai"); } 

  C.E: Incompatible types found :int      required: boolean. 

char ----

java provides support for Unicode i.e it supports all world wide alphabets. Hence the size of char in java is 2 – bytes. And range is 0 to 65535. 

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