Objects First With Java - Chapter 1

Course Contents• Introduction to object-orientedprogramming…• …with a strong softwareengineering foundation…• …aimed at producing andmaintaining large, high-qualitysoftware systems.Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 3

Buzzwordsresponsibility-drivendesigninheritanceencapsulatioiteratorscohesionoverridingjavadocncouplininterface gcollectionclassesmutator methodspolymorphic methodcallsObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 4

Goals• Sound knowledge of programmingprinciples• Sound knowledge of objectorientation• Able to critically assess the qualityof a (small) software system• Able to implement a small softwaresystem in JavaObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 5

BookDavid J. Barnes & Michael KöllingObjects First with JavaA Practical Introduction using BlueJ4th edition,Pearson Education, 2008ISBN 0-13-606086-2.Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 6

Course overview (1)• Objects and classes• Understanding class definitions• Object interaction• Grouping objects• More sophisticated behavior - libraries• Well-behaved objects - testing,maintaining, debugging• Designing classesObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 7

Course overview (2)• Inheritance• Polymorphism• Extendable, flexible classstructures• Building graphical user interfaces• Handling errors• Designing applicationsObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 8

DemoObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 9

Fundamental concepts• object• class• method• parameter• data typeObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 10

Objects and classes• objects– represent ‘things’ from the realworld, or from some problemdomain (example: “the red cardown there in the car park”)• classes– represent all objects of a kind(example: “car”)Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 11

Methods and parameters• Objects have operations whichcan be invoked (Java calls themmethods).• Methods may have parameters topass additional informationneeded to execute.Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 12

Other observations• Many instances can be createdfrom a single class.• An object has attributes: valuesstored in fields.• The class defines what fields anobject has, but each object storesits own set of values (the state ofthe object).Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 13

StateObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 14

Two circle objectsObjects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 15

Source code• Each class has source code (Javacode) associated with it thatdefines its details (fields andmethods).Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 16

Return values• Methods may return a result via areturn value.Objects First with Java ­ A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling 17