— Scott McNealy, Sun Microsystems Chairman, President and ceo

False
False
False
True
False
False
True or False

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314
 
chapter 10
Exercise Solutions
import java.util.*;
import static java.lang.System.out;
class FullMoons {
static int DAY_IM = 1000 * 60 * 60 * 24;
public static void main(String [] args) {
Calendar c = Calendar.getInstance();
c.set(2004,0,7,15,40);
long day1 = c.getTimeInMillis();
for (int x = 0; x < 60; x++) {
day1 += (DAY_IM * 29.52)
c.setTimeInMillis(day1);
out.println(String.format(“full moon on %tc”, c));
}
}
}
File Edit Window Help Howl
% java FullMoons
full moon on Fri Feb 06 04:09:35 MST 2004
full moon on Sat Mar 06 16:38:23 MST 2004
full moon on Mon Apr 05 06:07:11 MDT 2004
Notes on the Lunar Code Magnet:
You might discover that a few of the 
dates produced by this program are 
off by a day. This astronomical stuff 
is a little tricky, and if we made it 
perfect, it would be too complex to 
make an exercise here.
Hint: one problem you might try to 
solve is based on differences in time 
zones. Can you spot the issue?
code magnets 
solution

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11

exception 
handling 
this is a new chapter
315
Stuff happens. The file isn’t there. The server is down.
 
No matter how 
good a programmer you are, you can’t control everything. Things can go wrong. Very wrong. 
When you write a risky method, you need code to handle the bad things that might happen.
But how do you know when a method is risky? And where do you put the code to handle the 
exceptional situation? So far in this book, we haven’t really taken any risks. We’ve certainly had 
things go wrong at runtime, but the problems were mostly flaws in our own code. Bugs. And 
those we should fix at development time. No, the problem-handling code we’re talking about 
here is for code that you can’t guaranatee will work at runtime. Code that expects the file to be 
in the right directory, the server to be running, or the Thread to stay asleep. And we have to do 
this now. Because in this chapter, we’re going to build something that uses the risky JavaSound 
API. We’re going to build a MIDI Music Player.
Risky Behavior
Sure it’s risky, 
but I can handle it if 
something goes wrong. 
Make it Stick

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