introduction to java and features

oop features:

class
object
Inheritence
polymorphism
Data Abstraction
Encapsulation





java versions:

java jdk1.0,1.1
java2 1.2,1.3,1.4
java5 1.5
java6 1.6
java7 1.7
java8 1.8



j2se
j2ee
j2me

1
simple: pointers eliminated
app development time is less
Bytecode
bytecode os independent,jvm os dependent
jit compiler (just in time)
API

paltform independent:

MultiThreading:



Robust: exception

dynamic:   static---mem wastage,overlapping

security: api





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Primitive type Size Minimum Maximum Wrapper
type
boolean 1-bit – – Boolean
char 16-bit Unicode 0 Unicode 216- 1 Character
byte 8-bit -128 +127 Byte
short 16-bit -215 +215 – 1 Short
int 32-bit -231 +231 – 1 Integer
long 64-bit -263 +263 – 1 Long
float 32-bit IEEE754 IEEE754 Float
double 64-bit IEEE754 IEEE754 Double
void  Void


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The primitive data types also have “wrapper” classes for them.
That means that if you want to make a non-primitive object
 on the heap to represent that primitive type, you use the
associated wrapper.


Character C = new Character('x');


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variables

declaration
definition
Rules to define

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constants


final int a;

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final classes not support inh
coomon to all final methods

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Methods

definition
calling
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Method overloading
Method Overriding

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data security

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