Transcript Java Software Solutions Chapter 2 Objects and Primitive Data 1

Java Software Solutions
Chapter 2
Objects and Primitive Data
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Object-Oriented Programming
 This course introduces the idea of developing
software by defining objects:
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Objects with which we can interact via our programs.
Objects which can interact with each other as our
programs execute.
 Your programs will define software objects that model
objects in the real world.
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Data that describes an instance of an object at a point
in time will be stored in the computers memory during
program execution.
Methods will be written that will allow an object to
change its state and the state of other objects by
changing their stored data.
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An Example
 Suppose we write a program that models the interaction
between a driver and an automobile.
 Our program could create a driver object and an
automobile object. The description of these objects could
become quite complex, but just to keep things simple:
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Suppose the automobile object has a method named
changeSpeed and an instance variable named speed
that holds the current value of the automobile’s speed.
The driver object could send the automobile object a
message (asking the automobile to change its speed) by
calling the changeSpeed method and passing to it a new
value for speed.
The changeSpeed method would store the new speed
value in the automobile’s speed instance variable. The new
value could then be used in another of the automobile’s
methods, perhaps called computeLocation, to compute
the automobile’s changing location.
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