New Mock Exam Questions

[William Brogden]

In preparation for the new edition of my Java 2 Exam Cram book, Marcus Green and I have been creating some new questions. We would like to get your reaction to these questions, so give it a try if you get a chance.
Starting point to new question collection.
The test headed "Experimental Test C" is the newest material. Use the "show answer" button to see the author's comments.
I am particularly interested in hearing from you if you find any errors or unfair questions. Please use the Email to Author button because it provides the most information on the question.
[ December 15, 2002: Message edited by: William Brogden ]

[Greg Windwall]

For the following:
boolean hashFlag = (x.hashCode() == y.hashCode());
boolean equalsFlag = x.equals( y );
boolean eqFlag = ( x == y ) ;
I would think the statement:

"If equalsFlag is false, then eqFlag must be false"
should be true. If equalsFlag is false, then the contents of x and y must be different, or they are of different types. Either way, they can't occupy the same memory location.
The exam was helpful, it pointed out my weak spots. You have a passing grade of 61.5% - isn't the real exams passing grade lower, something like 51%?
Thanks,
Greg
[ December 15, 2002: Message edited by: Greg Windwall ]
[ December 15, 2002: Message edited by: Greg Windwall ]
[ December 15, 2002: Message edited by: Greg Windwall ]

[Greg Windwall]

For this question I got radio buttons, allowing
only one selection. I believe more than one
is correct.
public class SomeTest {
static int[] x ;
static int[] y = new int[20] ;
static String[] s1 ;
static String[] s2 = new String[20] ;
The following options make statements about the results of various operations executed before any change has affected these variables. Which of these statements is true?
a The logical test x == null will return true.
b The value retrieved by addressing y[ 0 ] is 0.
c Addressing the element s1[ 1 ] produces a null value.
d Addressing the element s2[ 1 ] produces an empty String.

[Greg Windwall]

For the code:
public class TestQ24 {

public static final StringBuffer style =
new StringBuffer("original");
public static void main (String[] args){
TestQ24 tq = new TestQ24();
tq.modify( style );
System.out.println("Now " + style );
}
public void modify( StringBuffer sb ){
sb.append(" is modified" );
}
}
the selections below should have "Now ...":
a Compiler objects to modification of a static final variable
b Output of "original"
c Output of "original is modified"
d Output of "is modified"

[William Brogden]

Thanks to everybody who has tried the questions and spotted problems. You could mail me directly if you like at [e-mail]
I just put an arbitrary passing percent on the test since we have not gathered enough results to compare with the real test difficulty.
Bill