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Java OOPS
Every object have attributes and behaviour.
Each Piece of the knowledge is called an attirbute.
The Functionality of the object is behavior.
Some Objects Manipulate other objects.
Object can be part of the other object.
Object Oriented Programming:
OOPS is aProgramming Language model ,organized around object and data.
OOP Advantages:
Re-usability
Flexibility
Extensiblity
Real world modeling is easy with OOP Implemention.
Promotes the reuse of the Code : the code used to define an object can be shared by several objects of an application.
Provides flexibility in the modification of an existing application.
Helps with the maintainance of code,simplified by reducing the dependencies.
OOP Core Concepts:
Back bone of the OOP are,
Class
Object
Abstraction
Encaptulation
Inheritance
Polymorphism
Class:
A class is the bluprint from which individual objects are created.
A class is the Template .
Object:
Real World Things are called the Objects.
Ex:Dog,Desk Bicycle
Characteristics of the Objects:
State
Behavior
An Object stores its state in the fields
Exposes the behavior through methods.
Abstraction:
Abstraction is the process of reducing the information content, in order to retain only the information relavant for a particular purpose.
Attributes of the Attributes:
Coherence.
Conciseness.
Identity.
Completeness.
Encapsulation:
Encapsulation is a process by which you can hide data fields and methods inside the Object.
Use of Encapsulation seperation of an interface from an implementation.
Inheritance:
Derive some properties from their parent object.
New instance of the object inherits all the data and methods from the tested base object.
Polymorphism:
Perform one more functions in a different way.
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| Author: srinivas 19 Jun 2008 | Member Level: Gold Points : 2 |
SCJP Java module 1:
Robustness:
Eliminates Pointer arithmetica nd memory management
Interpreted environment - Reduces the compile link load test cycle.
Code Portability - Run on multiple OS
JVM --Java Virtual Machine
Specification provides the hardware platform.
Compiler takes java application source code and generates bytecode.
Bytecodes are machine code instructions for the JVM.
Garbage Collection :
memory allocation and dellocation at run time.
Garbage collection happens automatically during the lifetime of a java techo=nology program.
Avoids memory leaks.
JRE ( Java Run time Environment):
Compiled java Programs converted into byte codes.
Bytecodes are stored in .class file.
loaded, checked and run in an interpreter.
Java Hotspot(JIT).
JVM( Java Virtual Machine) Tasks :
Loads Code.Class loader.
Verifies Code.byte code Verifier
Executes Code.run time interpreter
Compile Time Errors:
1. Javac Command Not Found ( Path not set Properly) /bin
2. Cannot resolve the Symbol .(method name incorrect.)
3. Class Count name of the file and class file name must be same.
Run time Errors:
1.can't find the class. Class name specified in the command line is different from the .class file name.
2.Exception in the Main thread. static main not available for the interpreter to execute.soem proble with main parameters or
signature.
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| Author: mohan 19 Jun 2008 | Member Level: Gold Points : 1 |
May i know the differences between the scjp 065 and 055 exam differences and what is the portion for 065?
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| Author: srinivas 20 Jun 2008 | Member Level: Gold Points : 2 |
Kathy Sierra SCJP Guide ..
Kathy Sierra SCJP GUIDE
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