JavaRanch Exclusive! temporary K&B 5 errata

[Bert Bates]

Hi guys,

Haven't got this up on the website yet, but here's the current errata for the K&B SCJP 5 book. If I've missed any let me know in this thread, or better yet in an email!

hth,

Bert

  
SCJP 5 - Errata2/28/06
 
Page  type           details
 
9        suggest          Be explicit that Listeners MUST end in 'Listener'
 
74 &     errata           Q-2  change all 4 'Bark' to 'void'
77
 
115      suggest          last sentence before exam watch should be:
 
                                If any superclass in its inheritance tree has already provided  
                                concrete (i.e., non-abstract) method implementations, then, 
                                regardless of whether the superclass declares that it implements 
                                the interface, the subclass is under no obligation to re-implement 
                                (override) those methods.
 
236     suggest           Add this explanation after the bullets:
 
                                When == is used to compare a primitive to a Wrapper, the Wrapper 
                                will be unwrapped to its primitive value, and the comparison will 
                                be made between the two primitive's values.
 
259 & 
266  suggest         To avoid confusion with the 'wrapper pool':
 
                                 Q-2, Short story = 5;  s/b  Short story = 200;
 
454      errata           2nd paragraph:
 
                                defaultReadObject()   s/b:
                                readObject()
 
505 &    errata         Q-12 the phrase  "dir1" and "dir1"   s/b
517                                                   "dir1" and "dir2"
 
538      errata          In the figure, LinkedHashMap should be a subclass 
                                of HashMap
 
620 &    errata          Q-16   List<? super E>   s/b
634                                    List<E>
  

[ March 01, 2006: Message edited by: Bert Bates ]

[jothi devika]

Bert

I purchased the book last week.The information which you hav posted wil be useful me.

The K&B book is very nice.
Thanks a lot for ur wonderful work.

warm regards
devika

[Sayan Bhattacharya]

Great Bert!thanks a lot!!

[Edisandro Bessa]

Hi Bert,

I think there's one more errata to our list. I've just sent an email too.

Chapter 9, Page 711, Paragraph 5th

Original Statement :
5. Within the block, output the StringBuffer 100 times and then increment
the letter in the StringBuffer. You can check Chapter 5 for StringBuffer
methods that will help with this.

Replaced one :
5. Within the block, output the StringBuffer 100 times and then increment
the letter in the StringBuffer. You can check Chapter 6 for StringBuffer methods that will help with this.


Chapter 5 no longer mention StringBuffer or StringBuilder objects.

[Graham Walsh]

Hi,

I've got the 1.4 book (darn, I should have got the 1.5!). Where can I find errata for the 1.4 book?

thanks much

GrahamO

[Barry Gaunt]

Originally posted by Graham Walsh:
Hi,

I've got the 1.4 book (darn, I should have got the 1.5!). Where can I find errata for the 1.4 book?

thanks much

GrahamO

K & B 1.4 errata

[Michael Creech]

Here is some more errata I've compiled that weren't listed:

p.45, Synchronized Methods, "We'll discuss this nearly to death in
Chapter 11"-->"We'll discuss this nearly to death in
Chapter 9" [there is no chapter 11]

p. 175, figure 3-1, String object "Aiko"-->"Fido"

p.253 "...don't put any essential code into your finalize()"-->same
text but font for 'f' in finalize fixed to be same as rest of the
word

p.258 "Using == with wrappers is tricky; wrappers with the same small
values (typically lower than 127), will be ==, larger values will
not be ==." --> this is only true for *boxed* wrappers and ones
lower then 128.

p322, Exam Watch, "But the only variable that can be assigned (rather
than tested against something else) is a boolean; all other
assignments will result in something non-boolean, so they're not
legal..."

This may be precisely true, but somewhat misleading in that
Boxing adds a bit on this since:

Boolean boo = false;
if (boo = true) {} *will* compile and execute.

p441, "Take special note of the what the readline() method
returns."-->"Take special note of what the readline() method
returns."

p492, under Serialization, "The key method you invoke to serialize an
object is writeObject(), and to deserialize an object invoke
readMethod()." --> change readMethod() with readObject().

p497, "You should understand the Pattern compile() method and the
Matcher matcher(),...--> change matcher() to matches()

p513, #7, alternate solution is to have 'try' moved down to just
enclose 'file.createNewFile();', since mkdir() doesn't throw
any checked exception.

p562, "It's important to know that the order of objects printed in the
second for loop is not prdictable: HashSets and LinkedHashSets
do not guarantee any ordering."

I believe this is incorrect about LinkedHashSets, which
guarantee ordering by insertion order.

[Deepak Bala]

page 364 , you missed a semicolon when calling doStuff()

[Kristian Perkins]

Here is a couple of things I found:

page 233 in the table Boolean.valueOf(String) is listed as throwing a NumberFormatException but it does not (only the instances of java.lang.Number throw NFE).

page 439 There are two ways to create a file: point 2 states that FileReader and FileInputStream will create a file if it doesn't exist. This is incorrect, these classes will throw a FileNotFoundException if the file does not exist.

Kristian
[ April 10, 2006: Message edited by: Kristian Perkins ]

[Kristian Perkins]

Sorry to say I have a couple more:

page 216: The second code sample under the section "Initializing Elements in a Loop" shows:

for (Dog d : myDogs)
    d = new Dog();

is incorrect in regard to initialising the myDogs array. New Dog objects will be created, but they will be thrown away and all elements in the array will remain null (I know because I have been bitten by this before).

page 370: Chapter locations of some of the Exception types seem to be off, i.e. NumberFormatException is in chapter 3 not 6, IllegalArgumentException in chapter 5 not 3, IllegalStateException I couldn't find and NoClassDefFoundError is hinted at in chapter 10 such as pg. 768 "... javac complains that it can't find a class ..." but doesn't mention NoClassDefFoundError specifically.

By the way, this book is full of great content for the 1.5 exam and is highly recommended.

Kristian
[ April 10, 2006: Message edited by: Kristian Perkins ]

[Djoga Djogov]

Hi Kristian,
Why will the new Dog objects be thrown away and not assigned to the array elements? Please explain it.

[Kristian Perkins]

with the for each loop, you don't have direct access to the array references, you only have a copy of the references in the array so you cannot change the original Object references inside the array.
the previous code is equivalent to this:

for (int i = 0; i < myDogs.length; i++) {
    Dog d = myDogs[i];  // which is null
    d = new Dog();      // assigns reference d to a new instance of
                        // Dog object, but reference myDogs[i] is
                        // still null.
    // end of this iteration, reference d out of scope
    // and the Dog object created is eligible for GC.
}

The for each loop can't change the reference of the array elements, where as the old style for loop listed here can (because you have direct access to manipulate each reference in turn through myDogs[i] = new Dog()).

Hope that helps.
Kristian

[Higgledy Smith]

Originally posted by Kristian Perkins:
with the for each loop, you don't have direct access to the array references, you only have a copy of the references in the array so you cannot change the original Object references inside the array.
the previous code is equivalent to this:

for (int i = 0; i < myDogs.length; i++) {
    Dog d = myDogs[i];  // which is null
    d = new Dog();      // assigns reference d to a new instance of
                        // Dog object, but reference myDogs[i] is
                        // still null.
    // end of this iteration, reference d out of scope
    // and the Dog object created is eligible for GC.
}

The for each loop can't change the reference of the array elements, where as the old style for loop listed here can (because you have direct access to manipulate each reference in turn through myDogs[i] = new Dog()).

Hope that helps.
Kristian

Kristian,
Is this because in a "for each" loop you are really using the some iterator method that has a type Dog? And as you stated not really access the reference to the Dog Array?

[Djoga Djogov]

Thanks Kristian.
I got it now. Looks like this is a flaw in the new for each loop which makes it pointless to some extend, because initializing arrays would be one of its main purposes.
Djoga

[J Sato]

Didn't see this one here...

p541 paragraph 1 - typo "king of order" should be "kind of order"

[Lavanya Raguram]

259 &
266 suggest To avoid confusion with the 'wrapper pool':
Q-2, Short story = 5; s/b Short story = 200;


now wat will be the difference n can a short wrapper be able to store more than 127?

[Higgledy Smith]

I am not trying to be dense. But what does this mean in Bert's post to this thread:

bump

[Bert Bates]

Hey Lavanya - let's keep this thread just for the errata - there is another thread that's busy discussing this topic thanks

Higgledy - bump just means if you add a post to an old thread it "bumps" it back to the front page

[Oscar Gonzalez]

In the top of the page 319 there is a sentence that says:

"Once an else if succeds, none of the remaining else ifs or elses will be tested"

The word elses suggest that you can have zero or more "else" clauses which is not true.

[vivien siu]

OMG.... I should have seen this thread before buying it yesterday!!

Hi Bert! So where can we check the finalized errata?

[Kristian Perkins]

Here ara a few more:

page 234: replace both occurrences of

System.out.println("y = " + i);

with

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

page 381:
the swich code sample, the case statements for 1, 2 and 3 need break statements to prevent fall through to the "We're never supposed to get here!" default case. Also in the paragraph below replace 'x must be either 2, 3 or 4' with 'x must be either 1, 2 or 3'.

page 631: Q 13 Answer, last sentance replace 'methods are not defined in the List interface.' with 'methods are not defined in the Arrays or Collections classes.'
[ April 10, 2006: Message edited by: Kristian Perkins ]

[Bert Bates]

I sent an email off to the publisher late last week to get started on the official errata page - we'll let you know when it's available.

[gaurav singhal]

Bert pg 94 i feel that this example is wrong

public class Horse extends Animal {
private Halter myHalter;//it should be private Halter myHalter = new Halter();
public void tie(LeadRope rope) {
myHalter.tie(rope); // Delegate tie behavior to the
// Halter object
}
}
public class Halter {
public void tie(LeadRope aRope) {
// Do the actual tie work here
}
}

plz confirm

[Barry Gaunt]

p581 Exam Watch at bottom of page:
...even if that Object reference points (yuck) to an Integer(or some other primitive) on the heap.

Primitive? On the heap? It should be Wrapper object, surely?
[ April 11, 2006: Message edited by: Barry Gaunt ]

[Eddie Fu]

On page 682, under exam watch:

Runnable r = new Runnable();
...

I don't think it is legal since you cannot instantiate an interface.

[Kristian Perkins]

Eddie,

No it is not legal and is mentioned in the updated errata

[Bert Bates]

This thread is locked.

The updated K & B errata list is here:

https://coderanch.com/t/253802/java-programmer-SCJP/certification/Updated-Errata