Barry Boones Exam Doubt

[anand phulwani]

Question 13: There are a number of labels in the source code below. These are labeled a through j. Which label identifies the earliest point where, after that line has executed, the object referred to by the variable first may be garbage collected?

class Riddle { 
public static void main(String[] args) { 
String first, second; 
String riddle;
if (args.length < 2) 
return;
a: first = new String(args[0]); 
b: second = new String(args[1]); 
c: riddle = "When is a " + first;
d: first = null; 
e: riddle += " like a " + second + "?"; 
f: second = null; 
g: System.out.println(riddle); 
h: args[0] = null; 
i: args[1] = null; 
j:  
}
}

Select the one right answer.

a.d: (What The Awnser Is)
b.e:
c.h:
d.i:
e.j: (what I think)

Can anyone explain me why ,i have read the explaination given by Boone but couldnt get it.

i think its last line j: becuase although variable first is nulled at line d: but its refernce is still holded by line c: by the variable riddle.

Thanks,
With Regds,
Anand.

[Seb Mathe]

riddle holds a new String (immutable) object = "When is a <arg0>", riddle does'nt hold a reference to "When is a " and a reference to first.

riddle = "When is a " + first
is equivalent to
riddle = "When is a ".concat(first), which creates a new String.

There's no more reference to the String created at (a) after first=null.
[ October 03, 2005: Message edited by: Seb Mathe ]