Errata

Even after looking at the Answers I cannot convince myself if the lines added at the "A" are cumulative or placing one at a time. Without knowing I don't know which way to enter the lines of code.

The line of code which reads:

System.out.println("result = " + result);

I think it should be:

System.out.println("result = " + limit);

I'm new to Java streams so I might not be correct. Please let me know.

Thanks,

Kevin Abel

A) Ready-Bake Code location is:
orei.ly/hf.Java_3e_examples

I didn't see the period between hf and java. I was contacting the publisher and they were telling me that they can see the code with the link.

B) I kept seeing the changes to the code at the ready bake site.
I was clicking on the right side that is the description . I should have been using the left side hyperlink. It seem obvious now, but I was confused for months not knowing why I could not get to the code.
Ron McLead on the Ranch solved the mystery.

I was clicking on the last change column instead of the name column.

Item 2 reads: "The compiler check for errors and won't let you compile..." It should read "The compiler check for SYNTAX errors and won't let you compile".

On page 8, it says "at least one main method", which I think it should be "exactly one main method". On page 9, it says "running a program means telling the JVM to <<Load the MyFirstApp class [...] >>", that could be "running THE program", instead, because it can be confusing for a beginner.

The puzzle has an alternative correct answer (code).

In my opinion the way I did it felt more natural as the words "a noise", "annoys", "an oyster" flowed more naturally in seequence within the code itself and looked more clear. Like if other person would read my code he would be able to follow it more easy. Just my opinion.

class PoolPuzzleOne{
public static void main(String[] arges){
int x = 0;
while(x < 4){
System.out.print("a");
if(x < 1){
System.out.print(" ");
}
System.out.print("n");
if(x < 1){
System.out.print("oise");
x =x -1;
}
if (x==1){
System.out.print("noys");
}
if(x > 1){
System.out.print(" oyster");
}
System.out.println("");
x = x + 2;
}

}
}

P. 106 Output box in the lower right corner says "hit" followed by "passed" but the string "passed" appears no where in the code on p 106 and does not appear in the compiled output.

Code as written does not compile. It needs the class declaration such as:

public class SimpleDotComGame {

along with the closing brace at the end of the example.

Hi,
The grid at page 140 shows letters for rows and numbers for columns.
But the Java code on next pages assume the opposite.
Example: the method getAlphaCoordsFromIndex() in the ready-bake-code at page 153 use letters as columns and numbers as rows.

Thanks!
JF
Note: I found that incoherence because i program a graphic version using Swing.

The GameHelper code, belonging to the Dotcom exercises one can find in the printed version and in the example code of the page has a bug. The code is not able to place a dotcom in the first line horizontally.

This: if ( x>0 & (location % gridLength == 0))

Should be: if (incr == 1 & x>0 & (location % gridLength == 0))

There are 2 errors in the function:
(starting from the beginning of Pg 153)

1. coords[x++] = location;
2. location += incr;
3. if (location >= gridSize) {
4. success = false;
5. }
6. if (x > 0 && (location % gridLength == 0 ) ) {
7. success = false;
8. }
....

error 1: Line 6, the x > 0 will always be true since x is incremented on Line 1.
error 2: should move Line 2 to the end of code section. For example, DotCom Locations of 4, 5, 6 will never be generated because in the iteration where location is 6, it is increased to 7 on Line 2 (assume horizontal), and success will be false on Line 3.

public String getName.

I think that the "{" is missing

End of arrow should point to ba[x].hunny = honeyPot instead of ... new Bear();

last two arrows have to be a line deeper.

"if it is less than the width, it'll be padded with zeroes"

...should be:

"if it is less than the width, it'll be padded with spaces. To pad with zeroes, specify a leading zero for the width (i.e., 06)".

1. @Don Cook

> static class ScaryException extends Exception {
> }

static keyword is not necessary, following code should be enought:

class ScaryException extends Exception {
}

----

2. I think, that return statement in method doRisky is not needed, imho code should be like this:

static void doRisky(String test) throws ScaryException {
System.out.println("start risky");
if ("yes".equals(test)) {
throw new ScaryException();
}
System.out.println("end risky");
}

----

// --------------------------------------------------------------------
// in the snippet marked (2) there is following code:
try {
Foo foo = new Foo();
foo.foof();
}
int y = 43;
} catch (FooException fex) {
System.out.println("handle FooException");
}

// --------------------------------------------------------------------
// it shold be rather like this (one bracket too much):

try {
Foo foo = new Foo();
foo.foof();
}
int y = 43;
catch (FooException fex) {
System.out.println("handle FooException");
}
// --------------------------------------------------------------------

The code as it is does work, but after it is finished something stays active because the player is not stopped when finished.
This can be solved by inserting the following code between "player.start();" and "} catch ...":

long length = player.getTickLength();
Thread.sleep(length*200);
player.close();

This happens at least another time in a similar piece of code on another page.

Couldn't find where MidiEvent event is used. Maybe this line isn't necessary and may be removed (the code compiles and works without it).

This program has a side effect. The first time you click the ?Change Label? button the frame is resized, and every time the frame is resized the paintComponent method is called by the JVM. This changes the color of the circle. You can prevent this by saving the ?startColor? and ?endColor? in instance variables, and use a boolean instance variable to change the color only when you click the ?Change Color? button. Note: you also need to set the color when you set up the panel.

Call to sequencer.setTempoInBPM(120) should probably be done before
sequencer.start().

In the method setUpGui() I am missing the middle line of the next three lines:

f.setContentPane(m1);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setBounds(30, 30, 300, 300);

And near the end of the page I am missing

long length = (long) (sequencer.getMicrosecondLength()/1000);
Thread.sleep(length);

sequencer.close();

as well, between "sequencer.setTempoInBMP(120);" and "} catch...".

Should add
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
to close the tread when we close the window, as-is we need to do a ctrl-x to get the command line back.

On my system: Windows Vista, Java 1.6.03, Java SE RE 1.6.03-b05, these programs do not release the CMD prompt on close.

I fixed it by adding:

abstract class MyExitListener implements WindowListener {

public void windowClosing(WindowEvent e) {
sequencer.stop();
}
}

as an inner class. Maybe there's a better way?

For loop at location begins with the following:

for (int = 0; i < dirContents.length; i++) {

However this code snippet won't compile in a program without including "()" after "length", as follows:

for (int = 0; i < dirContents.length(); i++) {

Program QuizCardPlayer has some issues:

1. if you click "Next Card" button before loading any quiz file then Exception will be thrown on console
2. you can only load one quiz, every another (after seeing message "That was last card") won't execute & it'll throw and Exception on console.

My solution for above issues is this patch:
---------------------------------------------------------------------------
--- a/hfj-en/src/ch14/QuizCardPlayer.java
+++ b/hfj-en/src/ch14/QuizCardPlayer.java
@@ -43,6 +43,7 @@ public class QuizCardPlayer {
display.setFont(bigFont);
display.setLineWrap(true);
display.setEditable(false);
+ display.setText("Load cards using menu!");

JScrollPane qScroller = new JScrollPane(display);
qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
@@ -51,6 +52,7 @@ public class QuizCardPlayer {
mainPanel.add(qScroller);
mainPanel.add(nextButton);
nextButton.addActionListener(new NextCardListener());
+ nextButton.setEnabled(false);

JMenuBar menuBar = new JMenuBar();
JMenu fileMenu = new JMenu("File");
@@ -126,6 +128,9 @@ public class QuizCardPlayer {
System.out.println("couldn't read the card file");
ex.printStackTrace();
}
+ nextButton.setEnabled(true);
+ display.setText("");
+ currentCardIndex = 0;
}

The "private JTextarea answer" reference declaration in the second line of the private variable code block is not used anywhere in the rest of the program. It appears to be superfluous.

The interface of the Quiz Card application allows the user to load more than one card set (sequentially). Loading a second card set after you've played with the first one produces problems.
At the end of method loadFile before the call to showNextCard, insert:

nextButton.setEnabled(true);

If you are following the text of the printed edition, insert also at the same point:
currentCardIndex = 0;

The scheme followed in the download code avoids this latter problem - looks like the authors (post publication) realised that, using the more up-to-date and much neater approach, they needed to initialise their Iterator but forgot earlier to initialise their iterator (

After reader.close(); should be the currentCardIndex attribute set to 0. Otherwise it's not possible to play again in the same running.

The os and is descriptors should be closed after usage

os.close();
is.close();

Note reads "Printwriter acts as its own bridge between character data and the bytes it gets from the Socket's...."

Seems that it should read "Printwriter acts as its own bridge between character data and and the bytes it sends to the Socket's..."

Problem
=======

Chat client won't close if You click "close" button.

My solution
=========

There is:

setUpNetworking();
frame.setSize(400, 500);
frame.setVisible(true);

It should be:

setUpNetworking();
frame.setSize(400, 500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);

The print statement:
System.out.println("balance is " + balance);
should be within the increment method. Otherwise, the program shows unordered balance output even after it is synchronized.

**Problem**

Presented solution (and the initial code magnets given to be resolved) won't
produce expected results each time when it's compiled & runned on Windows 7 (64 bit)
using Oracle's JVM as follow:

$ javac -version
javac 1.7.0_07
$ java -version
java version "1.7.0_25"
Java(TM) SE Runtime Environment (build 1.7.0_25-b17)
Java HotSpot(TM) Client VM (build 23.25-b01, mixed mode, sharing)

**Solution**

Changing code as below will make it more likely to achive the behaviour similar
to that which was expected in the book. Of course it'll produce different output
than was expected in book and the output won't allways be the same, because
each line is not an atomic (synchronized) operation.

Change 1 - change code in ThreadOne class:

for(int x=0; x < 98; x++) {
a.updateCounter(1000);

To this:
for(int x=0; x < 98; x++) {
System.out.println("--1: " + a.getCount());
a.updateCounter(1000);

Change 2 - change code in ThreadTwo classf from this:

for(int x=0; x<99; x++) {
a.updateCounter(1);
To this:

for(int x=0; x<99; x++) {
System.out.println("--2: " + a.getCount());

In the second code block (class Test)

the statemest is:
tree.add(new Book("How Cats Work");
instead of:
tree.add(b1);

becase b1 is already declared and instantiated above, plus there is one closing paranthesis missing.

There should only be three lines of "animal eating" output from the TestGenerics2 program, not six.

There is:

% java TestGenerics3

Should be:

% javac TestGenerics3.java

The two alternative versions of the signature of the generic method takeThing, i.e.

public <T extends Animal> void takeThing(ArrayList<T> one, ArrayList<T> two)

and

public void takeThing(ArrayList<? extends Animal> one,
ArrayList<? extends Animal> two)

are implicitly presented as equivalent, but they have different semantics. For example, under the assumption that Cat and Dog are subtypes of Animal,

takeThing(ArrayList<Dog>, ArrayList<Cat>)

is legal in the second version, but is illegal in the first version.

Class file located on Web Server that responds to client request should be named "RegisterServlet.class", not "MyServlet.class".

It is not necessary to import the java.io.* package in the DiceService.java program.

It is not necessary to import the java.io.* package in the MiniMusicService.java program.

It is not necessary to import the java.io.* package in the DayOfTheWeekService.java program.

The music won't stop if I close the Beatbox window without pressing the "Stop" button first.

I added
theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE), as in chapter 13.

The music won't stop if I close the Beatbox window without pressing the "Stop" button first.

I added
theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE), as in chapter 13.

the section in the final beatbox code contains a class called "MyPlayListener" that is not used anywhere.

also I found comments in the code that says "exactly the same" but its not the same ...for instance the use of the Iterator in the makeTracks method...this is not the same as found on page 423 in makeTracks.

also the use of numKey in the same method

BUT IT'S STILL A REALLY GREAT BOOK!!!

PROBLEM:

Missing semicolon in this line:

ObjectOutputStream out = new ObjectOutputStream(clientSocket.getOutputStream())

This causes compilation error.

SOLUTION

Code should be look like that:

ObjectOutputStream out = new ObjectOutputStream(clientSocket.getOutputStream());

When i looked up the index for Brain barbell, i found that the pages listed for it (33,167,188) were actually pointing t Brainpower and not brain barbell.

missing "*"
import java.io;
should be
import.java.io.*;

In the code for MiniMusicPlayer2 and MiniMusicPlayer3 (a few pages later), inside the for loop, there are three calls to "track.add()". On my version of Java (1.8.0_74) the notes will not play if event 176 (CONTROL_CHANGE) is added *between* events 144 (NOTE_ON) and 128 (NOTE_OFF). But, if the code is change to add 176 *first*, the notes play. I.e. change

track.add(makeEvent(144,1,i,100,i));
track.add(makeEvent(176,1,127,0,i));
track.add(makeEvent(128,1,i,100,i+2));

to

track.add(makeEvent(176,1,127,0,i));
track.add(makeEvent(144,1,i,100,i));
track.add(makeEvent(128,1,i,100,i+2));