The object oriented style involves constructing an object and then sending it messages to accomplish a desired task. In my case, you could say that I have an extensive list of messages that I respond to. In the Java style, this could be described as follows:
Object: Bill
Methods: walk()
talk()
cook();
teach();
and so forth.
The authors have provided several fun classes with which to experiment.
The Trick Mouse class provides 3 methods: hitWall(), speak( :String), and setTitle ( :String). The notation :String suggests that the method requires an argument of type String (i.e., anything between double quotes "). In class, we constructed several programs to illustrate its use.
//File: TestMouse.java
import CSLib.TrickMouse;
public class TestMouse
{
public static void main (String [] args)
{
TrickMouse bill = new
TrickMouse(); //Construct a TrickMouse
//named bill
bill.setTitle("Bill Goes Crazy!");
//Change the title of the window
//to "Bill Goes Crazy"
bill.hitWall(); //Tell
bill to hit the wall
}
}
We then tested the other TrickMouse methods.
//File: TestMouse2.java
import CSLib.TrickMouse;
public class TestMouse2
{
public static void main (String [] args)
{
TrickMouse bill = new
TrickMouse(); //Construct a TrickMouse
//named bill
bill.setTitle("Bill Goes Crazy");
//Change the title of the window
//to "Bill Goes Crazy"
bill.speak("Where's the wall?!!!!");
//Tell bill to speak
}
}
Finally, we developed a somewhat complicated script that had our mouse hitting the wall, responding with anguish, and then vowing never to do that again. This required resizing the TrickMouse window, relocating it, and adding a pause in the proceedings so that we could savor the results. The first two tasks were accomplished by exploiting one of the most useful features of Objected Oriented Programming languages, namely inheritance. We observed from the TrickMouse documentation that these objects inherit the methods associated with the Component class, among which were:
public void setSize(int width, int height)
and
public void setLocation(int x, int y)
In the latter, we noted that the coordinate system is centered at the upper left hand corner of the screen and runs to the right and down.
It was the authors' Timer class that gave us the method needed to slow down the action so that we could observe the evolution of our little script:
public static void pause(long msec)
Putting these all together, we arrived at the following:
//MyMouse.java
import CSLib.*; //imports ALL classes in the CSLib package
public class MyMouse
{
public static void main (String [] args)
{
//construct a TrickMouse object called mickey
TrickMouse mickey = new
TrickMouse();
mickey.setTitle ("Mickey hits the
wall!");
mickey.setSize (350, 200);
mickey.hitWall();
//static void pause (long msec) ==>
"class" method
Timer.pause (3000); //pause 3 seconds
TrickMouse minnie = new
TrickMouse();
minnie.setTitle ("Mickey yells!!");
minnie.setSize (350, 200);
minnie.setLocation (325, 250);
minnie.speak ("Ouch, that hurt!!!!");
Timer.pause (3000);
TrickMouse mighty = new
TrickMouse();
mighty.setTitle ("Mickey ponders the
future..");
mighty.setSize (350, 200);
mighty.setLocation (650, 500);
mighty.speak ("I'll have to be more
careful...");
}
}