— Scott McNealy, Sun Microsystems Chairman, President and ceo

synchronization 
questions

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networking 
and
threads
you are here
4
523
Code Kitchen
This is the last version of the BeatBox! 
It connects to a simple MusicServer so that you can 
send and receive beat patterns with other clients.
The code is really long, so the complete listing is 
actually in Appendix A.
your message gets sent to 
the other players, along 
with your current beat 
pattern, when you hit 
“sendIt”
Andy: groove #2
Chris: groove2 revised
Nigel: dance beat
dance beat
incoming messages from 
players. Click one to load 
the pattern that goes 
with it, and then click 
‘Start’ to play it.

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524
 
chapter 15
A working Java program is scrambled up on the fridge. Can 
you add the code snippets on the next page to the empty 
classes below, to make a working Java program that pro-
duces the output listed? Some of the curly braces fell on the 
floor and they were too small to pick up, so feel free to add as 
many of those as you need!
File Edit Window Help Sewing
% java TestThreads
one 98098
two 98099
Exercise
Code Magnets
class ThreadOne
class Accum {
class ThreadTwo
public class TestThreads {
Bonus Question:
Why do you think we used the 
modifiers we did in the Accum class? 
exercise: 
Code Magnets

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networking 
and
threads
you are here
4
525
try {
Thread.sleep(50);
Thread.sleep(50);
Code Magnets, continued..
counter += add;
return a;
implements Runnable {
public void run() {
return counter;
one.start();
a.updateCounter(1000);
Thread one = new Thread(t1);
try {
public static void main(String [] args) {
for(int x=0; x < 99; x++) {
} catch(InterruptedException ex) { }
private static Accum a = new Accum();
} catch(InterruptedException ex) { }
implements Runnable {
Accum a = Accum.getAccum();
Accum a = Accum.getAccum();
public void run() {
for(int x=0; x < 98; x++) {
two.start();
ThreadOne t1 = new ThreadOne();
ThreadTwo t2 = new ThreadTwo();
public void updateCounter(int add) {
private Accum() { }
public int getCount() {
System.out.println(“two 
“+a.getCount());
System.out.println(“one “+a.getCount());
public static Accum getAccum() {
private int counter = 0;
a.updateCounter(1);
Thread two = new Thread(t2);

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