General Java Questions I

Answer: Yes, have the constructor throw an exception. Formally, an object _will_ be

created (since the constructor is a method invoked after the actual method creation),

but nothing useful will be returned to the program, and the dead object will be later

reclaimed by Garbage Collector.

But the clean way is as another reply suggests, that you leave calls to the constructor

to a static factory method which can check the parameters and return null when

needed.

Note that a constructor   or any method in general   throwing an exception will not

"return null", but will leave the "assign target" as it was.

Tor Iver Wilhelmsen

 Q: What does mean "volatile"?

For the past couple of hours, I ve seen quite a few set of codes that has the _volatile_

keyword.

E.g.

private volatile somethingsomething....

What does it mean?

Answer: See JLS 2nd Edition, which just came out last year, still mentions it.

http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#36930

"A field may be declared volatile, in which case a thread must reconcile its working

copy of the field with the master copy every time it accesses the variable. Moreover,

operations on the master copies of one or more volatile variables on behalf of a

thread are performed by the main memory in exactly the order that the thread

requested."

Seems just like the idea in C++ and appears still to me present in the language.

Synchronization certainly has it place in many applications, that doesn t mean that

volatile is not longer used or part of the language.

Paul Hill

Q: If some method is deprecated does it mean that one get a chance not to find

this method in some Java version?

Answer: It means it *may* be dropped in a future version, but chances are it s still

there. I m not sure I ve seen any deprecated features actually being removed from an

API yet   often they re turned into no ops first, if they re dangerous.

Jon Skeet   http://www.pobox.com/~skeet

Q: suppose I put a file a.txt in package com.xyz and the try access it like following.

Will it work?

import com.xyz.*;

public class Hello{

   File f = new File("a.txt");

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