mock exam Q

[preeti khane]

public class Test026
{
static Test026 t = new Test026();
String str;
public static void main(String args[]) {
Test026 t = new Test026();
t.method("0");
}
void method(String str) {
str = str;
System.out.println(str);
System.out.println(t.str);
System.out.println(this.str);
}
}
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A: The output is:
0
null
null
B: The output is:
0
0
0
C: The output is:
0
0
null
D: The output is:
0
null
0

what is the answer? The mock exam says A... I thought it wud be D

[Anupam Sinha]

Hi Preeti
The answer is and should be A. Well its so because System.out.println(this.str); would refer to t.str, t which has been declared in the main method. If however in the main method if this is present t.str="0"; then it would print the option D.

[Yogi Gupta]

The answer is and should be A. Well its so because System.out.println(this.str); would refer to t.str, t which has been declared in the main method. If however in the main method if this is present t.str="0"; then it would print the option D

Scope of variable t defined in the main method is limited to main method only. It can not be accessed outside the method. System.out.println(t.str) would refer to the static variable t defined earlier and thus it will print null.

[Anupam Sinha]

Hi Yogi
I wasn't refering to System.out.println(t.str); statement. I was refering to System.out.println(this.str); and I didn't refer to the former one because in options A and D the only thing different was the last line. Both the first two line show the same thing. So I simply focussed on what was different. No doubt in method "method" t would indeed refer to the static t declared earlier.

[Michael Schmidt]

I think the reason why you're confused about "System.out.println(this.str)" is because of the first line in void method (String str), which sets "str=str". If this said "this.str=str", then answer D would be correct because you would've set the instance variable str = 0. As it is, you're (rather unnecessarily) setting local str = local str, which leaves the instance version of str untouched (default value = null).
I hope this helps.
Michael
[ June 07, 2003: Message edited by: Michael Schmidt ]
[ June 07, 2003: Message edited by: Michael Schmidt ]