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General <strong>Java</strong> Questions III<br />
But the clean way is as another reply suggests, that you leave calls to the<br />
constructor to a static factory method which can check the parameters and return<br />
null when needed.<br />
Note that a constructor - or any method in general - throwing an exception will not<br />
"return null", but will leave the "assign target" as it was.<br />
Tor Iver Wilhelmsen<br />
Q: What does mean "volatile"?<br />
For the past couple of hours, I've seen quite a few set of codes that has the<br />
_volatile_ keyword.<br />
E.g.<br />
private volatile somethingsomething....<br />
What does it mean?<br />
Answer: See JLS 2nd Edition, which just came out last year, still mentions it.<br />
http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#36930<br />
"A field may be declared volatile, in which case a thread must reconcile its working<br />
copy of the field with the master copy every time it accesses the variable. Moreover,<br />
operations on the master copies of one or more volatile variables on behalf of a<br />
thread are performed by the main memory in exactly the order that the thread<br />
requested."<br />
Seems just like the idea in C++ and appears still to me present in the language.<br />
Synchronization certainly has it place in many applications, that doesn't mean that<br />
volatile is not longer used or part of the language.<br />
--<br />
Paul Hill<br />
Q: If some method is deprecated does it mean that one get a chance not to find<br />
this method in some <strong>Java</strong> version?<br />
Answer: It means it *may* be dropped in a future version, but chances are it's still<br />
there. I'm not sure I've seen any deprecated features actually being removed from an<br />
API yet - often they're turned into no-ops first, if they're dangerous.<br />
Jon Skeet - http://www.pobox.com/~skeet<br />
this advice first was published on comp.lang.java.programmer<br />
Q: suppose I put a file a.txt in package com.xyz and the try access it like<br />
following. Will it work?<br />
import com.xyz.*;<br />
public class Hello{<br />
File f = new File("a.txt");<br />
...<br />
}<br />
it is not working for me. Is there any workaround?<br />
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