doubt in thread

[V Gala]

Hi V Gala,

The question you posted here was an actual exam question - so wherever you got this question, it's ILLEGAL - it's a violation of copyright laws, so please don't use questions from that site anymore.

thanks,

Bert

[actual exam question deleted - bert]

[ September 03, 2007: Message edited by: V Gala ]

[ September 04, 2007: Message edited by: Bert Bates ]
[ September 04, 2007: Message edited by: Bert Bates ]

[Jesper de Jong]

Please use a meaningful subject line (instead of just "doubt").

[Jianghu Li]

C is correct.

[V Gala]

Why A is False

[Jianghu Li]

Why a is correct?
The StringBuilder class was added in Java 5. It has exactly the same API as the StringBuffer class, except StringBuilder is not thread safe. In other words, its methods are not synchronized.

[V Gala]

Hi
I think StringBuffer is synchronized means all its method are synchronized

there can be two different thread invoking tostring method can interfere with each other
thread1->sb.append("<");
thread2->sb.append("bbn,mn");

then the code will not be thread safe

[Henry Wong]

For Java 5, which I assume that this mock test question is for, the answer is B. For Java 6, B and C can both be true.

Henry

[Henry Wong]

Originally posted by V Gala:
Why A is False

A is false because the toString() method is thread safe -- and this is true regardless of whether a string buffer or builder is used. The buffer is a local variable that doesn't escape the method, there is no way that it can be accessed by multiple threads.

Henry

[V Gala]

Thanks
I got it

[Lalit Bansal]

Can anyone please explain the code line by line.

Thanks in advance.

[Lalit Bansal]

Just an addendum to my previous post:

Also please explain the justification (i.e., why it is true or why it is false) for each of the option.

(Again)Thanks in advance.