Threads - Bill Brodgen

[Shah Chunky]

Hello all....
This is from Brodgen's 19 Hardest Questions
Given the following listing of the Widget class:
1. class Widget extends Thingee{
2. static private int widgetCount = 0 ;
3. public String wName ;
4. int wNumber ;
5.
6. static synchronized int addWidget(){ widgetCount++ ;
7. wName = "I am Widget # " + widgetCount ;
8. return widgetCount ;
9. }
10. public Widget(){
11. wNumber = addWidget();
12. }
13. }
What happens when we try to compile the class and use multiple Widget objects in a program?
-- options --
a - The class compiles and each Widget will get a unique wNumber and wName reflecting the order in which the Widgets were created.
b - The compiler objects to line 7.
c - A runtime error occurs in the addWidget method.
The answer Given was b because of static method accessing Non-Static variable
But suppose if v change the variable to Static,then what would have been the Answer. i.e. will the answer (a) be the correct Choice.
Thanks

[jeena jose]

choice a) will be the correct answer then.

[Sathi Chowdhury]

I suppose its b)

[Ravindra Mohan]

Hi Everyone,
When you will drop the "static" keyword from the <code>addWidget()</code> method then the answer would be
(A).
I guess your querry is answered now.
You may refer the following code and check for yourself.

class Thingee 
{
}
class Widget extends Thingee{
 static private int widgetCount = 0 ;
 public String wName ;
 int wNumber ;
synchronized int addWidget(){ widgetCount++ ;
wName = "I am Widget # " + widgetCount ;
return widgetCount ;
 }
public Widget(){
wNumber = addWidget();
}
public static void main(String as[])
{
Widget w1 = new Widget();
System.out.println(w1.wNumber);
Widget w2 = new Widget();
System.out.println(w2.wNumber);
Widget w3 = new Widget();
System.out.println(w3.wNumber);
}
}

Ravindra Mohan

[dave taubler]

No, answer a) says that each Widget gets its own unique number and name. I think you will find that when everything is done running, all of the Widgets created will have the same name (namely, "I am Widget # <last number created>" or whatever). Remember, we changed the wName variable to be static, so it is now shared by all of the Widgets.

[Cindy Glass]

Yeah, dave is right, each instance that you create will overwrite the name that the previous instance put in the static variable.