Transcript Classes
Classes Preparation • Scene so far has been background material and experience – Computing systems and problem solving – Variables – Types – Input and output – Expressions – Assignments – Objects – Standard classes and methods Ready • Experience what Java is really about – Design and implement objects representing information and physical world objects Object-oriented programming • Basis – Create and manipulate objects with attributes and behaviors that the programmer can specify • Mechanism – Classes • Benefits – An information type is design and implemented once and reused as needed • No need reanalysis and re-justification of the representation Static variables and constants // shared resource for all AirConditioner objects static public final int OFF = 0; Static public final int ON = 1; static public final int LOW = 0; Static public final int HIGH = 1; static public final int DEFAULT_TEMP = 72; • Every object in the class has access to the same static variables and constants – A change to a static variable is visible to all of the objects in the class – Examples StaticDemo.java and DemoStatic.java Instance variables • Instance variables are always initialized as soon the object comes into existence – If no value is specified • 0 used for numeric variables • false used for logical variables • null used for object variables • The constructor configures the object • Examples InitializeDemo.java