Question related to self test question in SCJP (Sierra/Bates) Java 6 book

[John Cochrane]

Hi,

I've just gone through the test questions for chapter 10 (Development) and don't understand the answer given.

It says that A is correct and C is not and I don't understand the difference. Why you can use the -classpath MyJar.jar in the javac invocation yet it's not allowed in the java invocation (Answer C)? Also, how does the java GetJar call in answer A find MyApp.Foo with a classpath specified?

Regards,
John

[James Tharakan]

I think you should post the question here. OR should have mentioned the question number. I had to go through all the question to find the actual question.
May be thats the reason , this post was unanswered for such a long time.

Why option A is correct,

When the classpath is not set in the command line or if the CLASSPATH environment variable is not set, then the classpath point to current directory.
For more calrification , check these links.

http://java.sun.com/javase/6/docs/technotes/tools/windows/javac.html
http://java.sun.com/javase/6/docs/technotes/tools/windows/java.html

The reason why option C is wrong is because GetJar.class is not reachable.
The command should be java -classpath MyJar.jar;. GetJar
Note the classpath is only pointing to test/*.jar but not to test/.....

[Sachin Adat]

John,
Please Search First
I got a minimum of 2 posts discussing this, here and here.

how does the java GetJar call in answer A find MyApp.Foo with a classpath specified

So I guess there is no answer to it......there should be a 5th option- None of the above...........I guess

[John Cochrane]

Hi Guys,

Thanks for the response and sorry for not putting the question number in the original post.

I'm happy now that I can see I'm not going crazy and the question was wrong :-)

Regards,
John

[Kedar Nath]

So does that mean that option A is wrong???
The link shows that classpath include current directory .
So it should work right ???

[Sachin Adat]

Kedar Nath wrote:So does that mean that option A is wrong???
The link shows that classpath include current directory .
So it should work right ???

I guess yes ....... it is wrong.

Kedar Nath wrote:The link shows that classpath include current directory .
So it should work right ???

No
You can see in the code that in GetJar, you are neither importing package myApp nor mentioning class Foo as myApp.Foo

public class GetJar {  
    public static void main(String[] args) {  
       System.out.println(Foo.d);  
    }  
 }  
   
 package myApp;  
 public class Foo {public static int d = 8; }  

[Kedar Nath]

K& B scjp6

3. public class GetJar {
4. public static void main(String[] args) {
5. System.out.println(myApp.Foo.d);
6. }
7. }

Surprising ! ! !
This is what i i have in my e-book myApp.Foo.d

[Sachin Adat]

Kedar Nath wrote:Surprising ! ! !
This is what i i have in my e-book myApp.Foo.d

Now, that's really surprising... because I have Foo.d in my e-book. Will check the hardcopy and tell tomorrow.
When did you buy the book, from where, has a new edition come out???

[Kedar Nath]

if it is this myApp.Foo.d, then its right. Isn't it.

Actually it downloaded from some site... illegal copy But with right ansewers i guess

[James Tharakan]

Even i have it as myApp.Foo.d

11. Given the following directory structure:
test-|
|- GetJar.java
|
|- myApp-|
|-Foo.java
And given the contents of GetJar.java and Foo.java:
3. public class GetJar {
4. public static void main(String[] args) {
5. System.out.println(myApp.Foo.d);
6. }
7. }

3. package myApp;
4. public class Foo { public static int d = 8; }
If the current directory is "test", and myApp/Foo.class is placed in a JAR file called MyJar.jar
located in test, which set(s) of commands will compile GetJar.java and produce the output 8?
(Choose all that apply.)
A. javac -classpath MyJar.jar GetJar.java
java GetJar
B. javac MyJar.jar GetJar.java
java GetJar
C. javac -classpath MyJar.jar GetJar.java
java -classpath MyJar.jar GetJar
D. javac MyJar.jar GetJar.java
java -classpath MyJar.jar GetJar

[Sachin Adat]

Kedar Nath wrote:Actually it downloaded from some site... illegal copy But with right ansewers i guess

This is the reason why sometimes I think piracy is not that bad.........
You buy and you have problem, and you download it and that has no problems.......... :roll:

[Sachin Adat]

James Tharakan wrote:Even i have it as myApp.Foo.d

Now this is really strange.......
James you can even copy and paste, mine is secured......cant even copy and paste..........

[James Tharakan]

Sachin Adat wrote:

James Tharakan wrote:Even i have it as myApp.Foo.d

Now this is really strange.......
James you can even copy and paste, mine is secured......cant even copy and paste..........

For this, i got only one thing to say....(which you said)

This is the reason why sometimes I think piracy is not that bad.........

[Sachin Adat]

[Kedar Nath]

So according to this statement, myApp.Foo.d
the program is correct ,RIGHT

[Ankit Garg]

Kedar Nath you must not use illegal copies of books. It is unethical in addition to being illegal. And anyone who has a legal copy of the book knows that this is probably an error in the book which Bert is looking after and soon an errata will be published in this regard...