Object-Oriented Programming through Java, Study notes of Object Oriented Programming

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OOP - JAVA

Object-Oriented Programming

Java

Margit ANTAL

Goals

1. Java Language
2. Objects and classes
3. Static Members
4. Relationships between classes
5. Inheritance and Polymorphism
6. Interfaces and Abstract Classes
7. Exceptions
8. Nested Classes
9. Threads
10. GUI Programming
11. Collections and Generics

Java language

● History

● Java technology: JDK, JRE, JVM

● Properties

● 'Hello world' application

● Garbage Collection

Short History

● 1991 - Green Project for consumer electronics market

(Oak language → Java)

● 1994 – HotJava Web browser

● 1995 – Sun announces Java

● 1996 – JDK 1.

● 1997 – JDK 1.1 RMI, AWT, Servlets

● 1998 – Java 1.2 Reflection, Swing, Collections

● 2004 – J2SE 1.5 (Java 5) Generics, enums

● 2014 – Java SE 8 Lambdas

Java technology

● JDK – Java Development Kit

● JRE – Java Runtime Environment

● JVM – Java Virtual Machine

JDK javac, jar, debugging

JRE java, libraries

JVM

Properties

● Object-oriented

● Interpreted

● Portable

● Secure and robust

● Scalable

● Multi-threaded

● Dynamic language

● Distributed

Hello World Application

HelloWorld.java

HelloWorld.class

javac HelloWorld.java

bytecode

java HelloWorld

Runtime

JVM

Garbage Collection

● Dynamically allocated memory

● Deallocation

− Programmer's responsibility (C/C++)

− System responsibility (Java):

● Is done automatically (system-level thread)

● Checks for and frees memory no longer needed

Module 2

Object-Oriented Programming

Object-oriented programming

Classes and Objects

● Class

● Attributes and methods

● Object (instance)

● Information hiding

● Encapsulation

● Constructors

● Packages

Declaring Classes

● Syntax

* class <class_name>{

<attribute_declaration>*

<constructor_declaration>*

<method_declaration>*

● Example

public class Counter{ private int value; public void inc(){ ++value; } public int getValue(){ return value; } }

Declaring Attributes

● Syntax

* <attribute_name>[= <initial_value>];

● Examples

public class Foo{ private int x; private float f = 0.0; private String name =”Anonymous”; }

Accessing Object Members

● Syntax