K&B - Practice Exams book - Full Exam II - Question 21

[Alvaro San Millan]

Hi guys,

Is someone doing these exams?

I the second full practice exam, question 21, page 204, the correct answers are D and F, but the answer F is not correct:

"When javac is invoked with a classpath option, and you need to find files in a JAR file, the name of the JAR file must be included at the end of the path."

I tried with this example:

---------------------------------------------
File A.java

public class A extends B {

static { System.out.println("A"); }

public static void main(String... args) {
System.out.println("main");
}
}

class B extends C {}

class C {}
---------------------------------------------

Current directory: temp

I compiled A.java and delete A.class, move B.class to dirB, create C.jar with C.class inside and move the C.jar to dirC, then delete C.class en temp

Final directory structure:

/temp
|---- A.java
|---- dirB
|---- B.class
|---- dirC
|---- C.jar

I tried this:

$javac -cp dirC/C.jar:dirB A.java

And the fila A.class is generated in /temp

Then, I tried:

$java -cp dirC/C.jar:dirB:. A

And the output was:

A
main

This means that the file C.jar does not need to be at the end of the path in the -cp option

Can anyone confirm me that F is not a correct answer?

Thanks in advance,

Alvaro

[Ash Gill]

You are correct my friend and the answer given in the book is also correct, i think you misinterpreted the answer. the following line:

"When javac is invoked with a classpath option, and you need to find files in a JAR file, the name of the JAR file must be included at the end of the path."

means that when you specify the -cp option, for eg:

$javac -cp dirC/C.jar:dirB A.java 

now the above line has two class paths: 1) dirC/C.jar & 2) dirB A.java. the 1st classpath has a C.jar at the end of the path and if you remove it, the C.jar won't be searched for any files. so, the answer statement is not talking about the order in which class paths 1) and 2) are specified.

[Alvaro San Millan]

Thanks Ash, you are right