Compiling errata for K&B, SCJP 6

[Bert Bates]

Hi Guys,

Okay, I've been hearing rumblings that it's past time to put together an errata list for K&B 6

I'm going to partially pull a 'Tom Sawyer' here - I'll start looking at the notes in my master copy of the book, AND if you guys want to use this thread to add any errata you know of, it'll help speed up the process. (I know, I'm just shameless.)

Thanks for your continued support!

Bert

[Ankit Garg]

Table 3-3, page 243, parseXxx method is not marked for Boolean class.

Chapter 3, self test answer 7, line 12 in code, getBidValue should be getValue.

A small change on page 618 will be good, I'm quoting the actual sentence

By saying <? extends Animal>, we're saying, "I can be assigned a collection that is a subtype of List and typed for <Animal> ........."

It would be better if it is

By saying List<? extends Animal>, we're saying, "I can be assigned a collection that is a subtype of List and typed for <Animal> ........."

as the explanation says about List but its not written in the first part.

Another suggestion, chapter 8 self test question 1, option B says

It does not have access to non-static members of the enclosing class

I would say that it should say it does not have DIRECT access to ...... (just a suggestion, I may be pushing it too much)

Another suggestion, chapter 10 page 798, it says

When searching for class files, the java and javac commands don't search the current directory by default

I've seen a few people get confused with this. If we add to it that this happens only if we use the -cp or -classpath flag, that would be great, the context is indeed the -cp/classpath flag so its not wrong, but I've seen a few people get confused with this.

The answer to the 11th question of 10th chapter is wrong (discussed many times like here).

One found in search here

I'll try to come up with some more as I find them...

[John Summers]

page 409 question 15
a)says "at line 4" and should say "at line 2".
b)in option E I think it should say "line 4" not "line 6"

[John Summers]

maybe this thread should be pinned near the top while the list is being compiled?

[Nidhi Sar]

Page 317 (ch 4): Question 8, line 10 should read

if (b1 || (b2 = true)) s += "x";
instead of:
if (b1 || (b2 == true)) s += "x";

That is what is there in the repetition of question 8 in the Answers section and also in the explanation of the answers.

[Emma Baillie]

This one is from the MasterExam CD, question 52 of the first open book test questions.

The class contains these variables:

int bal;
String code;
short rate;

The hashCode() function is defined as:

public int hashCode(){
  return (code.length()*bal);
}

The exam claims that the following code (option D) is ok for the equals method:

public boolean equals(Object o){
  return ((SortOf)o).code.length()*((SortOf)o).bal*((SortOf)o).rate
          == this.code.length()*this.bal*this.rate;
}

As far as I can see, if you have, for example, one SortOf object with code="foo", bal=1,rate=2 and another with code="bar",bal=2, rate=1 then their hashcodes are different (3 versus 6) but the equals method would report them as equal (since 3*1*2==3*2*1).

That would be bad.

[Martin Leon]

Page 281, Chapter 3 Test Question 7 Answer

The code from the answer does not match the code from the original question on page 272. The code on 281 will not compile because of line 12 -- there is no getBidValue() method defined.

Picky, I know, but confusing if you don't go back and look at the original question.

(THANKS FOR THE BOOK!)

[Christian Lombardo]

Page 458 Missing String type.

On the line #14: name = c.readLine("%s", "input?: ");

should be: String name = c.readLine("%s", "input?: ");

[Ajit Sawant]

On page 217 (chapter 3), part of the code is as follow:
class Foo{
static int size=7;
.... rest of the code.
The description on the page calls the variable size as an instance variable instead of static.

[Martin Leon]

Chapter 10 Self Test, Question 11, page 817, 818.

Foo.java declares that Foo is in the package myApp.

GetJar refers to "Foo.d" but does not either import myApp.* or refer to Foo.d by its fully qualified name. There is no way to get this code to compile.

[Martin Leon]

Chapter 10 Self Test, Question 12, page 818, 819.

This is just a typo I'm sure. Part of the question refers to the contents of "GetJar.java" but the rest of the question refers to the class GoDeep.

[Martin Leon]

Chapter 10 Self Test, Question 2, page 811, 812

My book has a "." after the "A" as part of the command line that is invoked. None of the answers have a ".", so none of them are correct.

Try it:

import static java.lang.System.*; 

class _ {
	static public void main(String... __A_V_) {
		String $ = ""; 

		for(int x=0; ++x < __A_V_.length; )
			$ += __A_V_[x];
		
		out.println($);
	}
}

java _ - A .

[Mike Vella Zarb]

Chapter 2: Object Orientation

Figure 2-8 "The effects of static on methods and variables":

class Bar{
    void go();
    static void doMore(){
        go();
}

Method void go() has a semicolon instead of curly braces. By the way, this code was demonstrating how a static method cannot access a non-static method.

[Joss Armstrong]

Chapter 5 - page 343

Java loops come in three flavors: while, do, and for (and as of Java 6, the for
loop has two variations).

I think this should read (and as of Java 5,...

Regards
Joss Armstrong

[Jerome Jacobsen]

Same issue on page 345 and 350

Joss Armstrong wrote:Chapter 5 - page 343

Java loops come in three flavors: while, do, and for (and as of Java 6, the for
loop has two variations).

I think this should read (and as of Java 5,...

Regards
Joss Armstrong

[Pasta Batman]

Is there going to be an official confirmation of the errata reported here? A normal errata sheet would be easier to use.

[Aldo Paradiso]

Hello, Bert.

First of all I must say that your SCJP 6 Study Guide book is great! You managed to explain complex topics with a rare combination of precision and humor. Thanks as lot!
Now the tough part: In chapter 5, section "Legal Expressions for if Statements" (page 333) the examples reported have been very confusing to me. I started to ask myself: "which is the operator precedence among the &&, ||, &, |, !=, and ^ operators?". In your book I could not find any answer. Yet, the topic is important if the student wants to fully understand (and remember) your examples and not fail this topic in the exam. I tried to infer myself the operator precedence based on your examples, and it was hard to figure it out. I could only browse other (online) material to find an answer. Only watching at the operator precedence table in the online Sun Java Tutorials trail (see Equality, Relational, and Conditional Operators section at http://java.sun.com/docs/books/tutorial/java/nutsandbolts/operators.html) I could clearly learn the precedence sequence and fully understand your examples.

It would be probably great if you insert (even a partial section of) the table in your next version of the SCJP guide.

Greeetings,

Aldo

[Pravin Sarkar]

Hi,

I have identified the following printing error in chapter 7, table 7-2

In that table, the first two entry is for "HashTable", i belive one of them should be "HashMap".

[Ninad Kulkarni]

@Java Baba
See JavaRanch Naming Policy

[Pravin Sarkar]

@Ninad
i have read the naming policy and my name follows all the obligations,
if still it needs to be changed,
then please moderators, do let me know.

[Justin Fleming]

removed

[Ankit Garg]

Java Baba wrote:i have read the naming policy and my name follows all the obligations,

No it doesn't. Please change it...

[Pravin Sarkar]

ok guys,, this is Java Baba.. and the name is changed,,,

[Justin Fleming]

Ok, not sure if this qualifies. Table 7-5 states that the * allows you to specify if the endpoints in a subset are exclusive, while they actually let you specify whether the endpoints are inclusive. I mean, in a way it lets you specify if they are exclusive, because thats another way to say the same thing by passing the opposite boolean value in.

Stating this the way it is in the book (that your specifying whether or not the endpoints are exclusive) I would expect that if a boolean value true is passed the endpoint should be exclusive, but instead they are inclusive. This was identified in test problem 11 at the end of chapter where I got the incorrect answer because of the confusion since I study from these tables. But now that I made this post I'm sure I will remember it correctly.

[Jerome Jacobsen]

p 571 2 instances of "Collections.sort(dvdlist)" should instead read "Collections.sort(dvdList)". Because the 'L' in 'dvdList' is uppercase on p570.

[Jerome Jacobsen]

p 590 in the NOTE the term "exclusive" should be "inclusive" instead to be consistent with the text above the paragraph and with the name of the boolean parameters in the relevant methods

[Jerome Jacobsen]

p 593, Table 7-6. some of the methods show the "public" access modifier and some don't. i imagine you want to remove the "public" as it is implied and uses up space in your table.

[Jerome Jacobsen]

p. 606, 3rd paragraph, first sentence:

"Keep in mind, then, that the problem of putting the wrong thing into a typed (generic) collection does not show up at the time you actually do the add() to the collection."

The sentence is not accurate for sorted collections. When doing an add() to a sorted collection, such as a TreeSet, the ClassCastException will occur during the add() operation.

The statement would be true if changed to read as below since Lists are not sorted collections.

"Keep in mind, then, that the problem of putting the wrong thing into a typed (generic) List does not show up at the time you actually do the add() to the List."

[Jerome Jacobsen]

p. 651, question 5:

I would argue that F is a more appropriate answer than E.

Your AccountManager class encapsulates its accountTotals map. Write access to it is limited to:
public void setBalance(String accountName, int amount)

No other code in AccountManager modifies the map values.

So there is no way to get a null value into accountTotals map.

Had the method signature been this instead, I would agree with your answer E:
public void setBalance(String accountName, Integer amount)

[Jerome Jacobsen]

chapter 9, p.756, 3rd sentence: I believe you meant IllegalMonitorStateException instead of IllegalThreadState exception.

[rich dubois]

I'm taking the sample tests on the CD that came with the book and there are a couple of questions that might have incorrect answers. Is this an appropriate forum for queries of this type?

Thanks

[Ankit Garg]

The forum is appropriate but the topic might not be as this topic is for the book not the mock exam. Create a new topic for the errors in the mock exams...

[Bert Bates]

Hi Rich and Ankit,

Actually, I'd prefer that errata on the CD are also listed here, it would help me out!

Also, THANKS to everyone for posting these! I tend to look into these in baches, so pretty soon I'll review all of these and give you all some feedback!

Bert

[mac praveen]

Also in page 558 fig 7.2 The interface and class hierarchy for collections,

The arrow symbol seems to be wrong.

HashSet implements Set but the arrow shows as 'extends'. Similarly for TreeSet and TreeMap (implements NavigableSet and NavigableMap respectively).

Forgive me if this has been reported elsewhere.

Thanks
Praveen

[Larry Chung]

In Certification Objective: Implementing an Interface (Exam Objective 1.2) (sorry no page number because I have only an online version of K&B, SCJP 6 that has no page numbering) I read the third point below and I am confused by the underlined part.

Is it possible that there is a typo there? Is it saying a concrete class must declare no subclasses of those declared by the interface method? What does that even mean???

"... a nonabstract implementation class must do the following:
- Provide concrete (nonabstract) implementations for all methods from the declared interface.
- Follow all the rules for legal overrides.
- Declare no checked exceptions on implementation methods other than those declared by the interface method, or subclasses of those declared by the interface method".

[Jerome Jacobsen]

p 448 comments in code at top of page next to "size = fr.read(in)" should have "bytes" replaced with "characters"

so it should read: "// how many characters read" rather than "// how many bytes read"

[Jerome Jacobsen]

Chapter 6, Self Test Question #11, p. 537

Your explanation states the B would be correct if a char[] was used instead of a String. For B to be correct it would have to look like this:

username: fred
hello fred
password:

It is missing the "hello fred" that was output on line 8 of the code.

[Jerome Jacobsen]

Chapter 9, Self Test Question 9:

The answer A is also correct: "It prints X and exits".

Sure, it also prints the Exception to standard error. But A is correct the way it is worded, in addition to G.

For example, on Windows try this (assuming you named your class Ch09Q09):
java Ch09Q09 2> output.err

The console output will be:
X

The output.err file will contain:
Exception in thread "main" java.lang.IllegalMonitorStateException
at java.lang.Object.wait(Native Method)
at Ch09Q09.main(Ch09Q09.java:6)

[Larry Chung]

Chapter 6 Self Test, Question 7, page (unknown because I am using an online version of K&B).

INCORRECT:
"...and the output is ''false true''; which set(s) of code fragments must be inserted? (Choose all that apply.) "

CORRECT:
"...and the output is ''false false''; which set(s) of code fragments must be inserted? (Choose all that apply.) "