Head First Object Exercise Chapter Two

[Richard Chambers]

OK, I'm back. I took a Java course this spring at the local college, and learned enough to know I don't know what I'm doing. I'm now starting Head First Java with a study buddy. We're in Chapter Two - Objects, It's one of those complete the code from a list of "snippet" things. We chose different codes, yet have the same output. Neither of us can explain why we chose the differing snippets other than we worked it through our heads and this one worked. Can someone explain which of the coding is preferred and why? or does it matter and both are right.

Thanks

My Coding

 
 
public class EchoTestDrive
{
public static void main (String[] args)
{
Echo e1 = new Echo();
Echo e2 = new Echo();
int x = 0;

while
(x < 4)
{
e1.hello();
e1.count = e1.count + 1;
if
(x == 3)
{
e2.count = e2.count + 1;
}
if
(x > 0)
{
e2.count = e2.count + e1.count;
}
x = x + 1;
}
System.out.println(e2.count);
}
}
 
class Echo
{
int count = 0;
void hello()
{
System.out.println("helloooo... ");
}
}   
 

His Coding

    
 
public class EchoTestDrive
{
public static void main (String[] args)
{
Echo e1 = new Echo();
Echo e2 = new Echo();
int x = 0;

while
(x < 4)
{
e1.hello();
e1.count = e1.count + 1;
if
(x < 4)
{
e2.count = e2.count + 1;
}
if
(x < 3)
{
e2.count = e2.count + e1.count;
}
x = x + 1;
}
System.out.println(e2.count);
}
}
 
class Echo
{
int count = 0;
void hello()
{
System.out.println("helloooo... ");
}
}

BTW -- My coding agrees with the book, so I assume his is wrong, but I can't show him why.

Thanks again
[ September 17, 2008: Message edited by: Richard Chambers ]

[Rob Spoor]

The exercise was to fill in some gaps and get the code to print 10 right?
Then if both of you have used available code snippets, you are both right.

It just happens sometimes - there is not one correct answer, but multiple.

[marc weber]

Add some println statements, and you will see the different behavior...

if (x == 3) {
  System.out.println("Assigning e2.count to " + (e2.count + 1));
  e2.count = e2.count + 1;
}
if (x > 0) {
  System.out.println("Assigning e2.count to " + (e2.count + e1.count));
  e2.count = e2.count + e1.count;
}

if (x < 4) {
  System.out.println("Assigning e2.count to " + (e2.count + 1));
  e2.count = e2.count + 1;
}
if (x < 3) {
  System.out.println("Assigning e2.count to " + (e2.count + e1.count));
  e2.count = e2.count + e1.count;
}