The Object Concept

An object is an encapsulation of data.

An object has

identity (a unique reference)

social security number (cpr), employee number, passport number

state, also called characteristics (variables)

hungry, sad, drunk, running, alive

behavior (methods)

eat, drink, wave, smile, kiss

An object is an instance of an class

A class is often called an Abstract Data Type (ADT).

Comments

case Java Keyword

The case is used to label each branch in a switch statement. Examples int arg = <some value>; switch (arg) { case 1: <statements> break; case 2: <statements> break; default: <statements> break; }

The catch keyword is used to define exception handling blocks in try−catch or try−catch−finally statements. Examples try { <block that may throw exceptions> } catch (<java.lang.Exception or subclass> e) { <code to handle exception e> } try { <block that may throw different exceptions> } catch (FooException e) { <code to handle FooException e> } catch (BarException e) { <code to handle BarException e> } try { <block that may throw exceptions> } catch (<java.lang.Exception or subclass> e) { <code to handle exception e> } finally { <statements that execute with or without exception> }

Polymorphism and Dynamic Binding

Polymorphism: One piece of code works with all shape objects. Dynamic binding: How polymorphism is implemented Take previous Shape class hierarchy remove inheritance remove general and abstract class Shape

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