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<a href="http://www.bruceeckel.com/javabook.html">Bruce Eckel's Thinking in Java</a>
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<H2 ALIGN=LEFT>
Exercises</H2>
<OL>
<LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Create
a new class called 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
with an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>int
gerbilNumber 
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">that&#8217;s
initialized in the constructor (similar to the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Mouse
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">example
in this chapter). Give it a method called 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>hop(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
that prints out which gerbil number this is and that it&#8217;s hopping. Create
a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and add a bunch of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
objects to the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
Now use the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>elementAt(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
method to move through the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and call 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>hop(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
for each 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Modify
Exercise 1 so you use an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Enumeration</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to move through the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
while calling 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>hop(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">In
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>AssocArray.java</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
change the example so it uses a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Hashtable</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
instead of an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>AssocArray</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Take
the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
class in Exercise 1 and put it into a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Hashtable</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
instead, associating the name of the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
as a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>String</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
(the key) for each 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">(the
value) you put in the table. Get an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Enumeration</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
for the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>keys(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and use it to move through the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Hashtable</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
looking up the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
for each key and printing out the key and telling the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>gerbil</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>hop(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Change
Exercise 1 in Chapter 7 to use a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to hold the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Rodent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s
and an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Enumeration</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to move through the sequence of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Rodent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s.
Remember that a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
holds only 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Object</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s
so you must use a cast (i.e.: RTTI) when accessing individual 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Rodent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s.</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">(Intermediate)
In Chapter 7, locate the 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>GreenhouseControls.java</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
example, which consists of three files. In 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Controller.java</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
the class 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>EventSet</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
is just a collection. Change the code to use a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Stack</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
instead of an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>EventSet</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
This will require more than just replacing 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>EventSet</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
with 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Stack</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">;
you&#8217;ll also need to use an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Enumeration</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to cycle through the set of events. You&#8217;ll probably find it easier if at
times you treat the collection as a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Stack</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and at other times as a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">(Challenging).
Find the source code for 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
in the Java source code library that comes with all Java distributions. Copy
this code and make a special version called 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>intVector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
that holds only 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>int</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s.
Consider what it would take to make a special version of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Vector</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
for all the primitive types. Now consider what happens if you want to make a
linked list class that works with all the primitive types. If parameterized
types are ever implemented in Java, they will provide a way to do this work for
you automatically (as well as many other benefits).
</FONT><LI><FONT FACE="Carmina Md BT" SIZE=5 COLOR="Black">	</FONT><FONT FACE="Da Vinci Extras" SIZE=39 COLOR="Black">e</FONT><a name="Chapter_9"></a><a name="_Toc375545361"></a><a name="_Toc407441453"></a><a name="_Toc408018588"></a></OL>
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