JAVA

JAVA

1. main features

   • object
     • it is the basic unit of oop. object refers to an actual instance of a class. every object must belong to a class.
   • Class
     • it is a blue print of an object . it defines the properties and behaviour of an objeci. a class is user defined used to abstract and implement data
   • data abstraction
     • a concept or idea not associated with any specific instance, it does not have any concrete existance. ie. hiding its internal details but only showing functionality
   • Encapsulation
     • it is the wrapping up of data and behaviour of an object into a single object
   • Inheritence
     • it describes the relationship between 2 classes, it has the ability to create classes that share attributes and methods of existing classes but with more specific features
   • Polymorphism
     • it means one task performed in several different ways. in java it is the ability to define more than 1 function with the same name

2. Tokens

   • literals/ constants
     • integer constant
     • real constant
     • character constant
     • string constant
     • boolean constant
     • null constant
   • variables/ identifiers
     • a variable is a named memory location which contains a valuewhich can b changed according to the circumstances. v can declare more than 1 variable of the same type
   • punctuaters
     • signs used as special characters in java ,.?
   • seperaters
     • special characters in java used to seperator variables or characters (){}[]
   • operaters
     • symbols used to perform arithematical or logical operators
       • arithematical: + - * /
       • logical: &&, //, !
       • relational: <, >, >=, <=, ==

3. Data Types

   • Primitive
     • Numeric
       • integer
       • real
     • non numeric
       • boolean
       • string
       • constant
   • Non Primitive
     • class
     • interface
     • array