Apple

Hello Mike,

Its the same code I have showed you (except that I changed variable names for simplicity), and there is no line of code that is missing. Where "a" is the EO property and when I check for it ( if(a != null) JRE throws NPE and when I check for if(a == null), JRE enjoys ), its throwing exception as stated. I believe this is a bug with JRE, and it seems to be fixed as per David's testing in later versions of JRE.

I think fix would be JRE shouldn't have unboxed it if its null... and they seems to have realized this mistake in later versions of JRE... But its wondering how a null & not null check differs in this world and they are not same from JRE perspective!!! If its an error it should have thrown error always...

Thank You,

Shravan Kumar. M

From: Mike Schrag <email@hidden>
To: Shravan Kumar. M <email@hidden>
Cc: WO Dev Group <email@hidden>
Sent: Sat, November 21, 2009 9:26:57 PM
Subject: Re: [OT] Weird Boolean/ Wrapper class bug

You're not pasting the real code, I don't think. I suspect you're just getting screwed by autoboxing in whatever code you're not showing. If you have:

Boolean a = null;

boolean b = a;

That will result in a NPE as auto-unboxing attempts to unbox a into a boolean, which throws a NPE. Somewhere in the code you didn't include is an unbox into a boolean (little b) of your null Boolean.

So, for instance:

Boolean a = null;

if (a) {

}

will NPE. Look more closely at the exact code, specifically the line of code that actually failing, and make sure you're not getting an unbox.

On Nov 21, 2009, at 10:23 AM, Shravan Kumar. M wrote:

Hello Group,

Boolean a = null;
if(a != null)
System.out.println("s");
else
System.out.println("n");

----------
Above code block raises NullPointerException, where as below one runs successfully!!! Same is the case with any wrapper class (Integer, Long, ...).
*Its wondering what it makes difference in checking (a != null) and (a == null)? Its just an Object check rt!*

Exact exception: java.lang.NullPointerException at booleanValue()
----------

Boolean a = null;
if(a == null)
System.out.println("s");
else
System.out.println("n");

Thank You,
Shravan Kumar. ymailto="mailto:email@hidden" target="_blank" href="mailto:email@hidden">email@hidden