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Thread-safety

John Daniel
Greenhorn

Joined: Mar 27, 2005
Posts: 20
I'm a Java newbie writing a small web application. I've been reading K&B's HF Servlet and JSP book at night in my attempt to catch up on the technology. Anyway in chapter 5, Kathy makes it very clear that servlet instance variables are not thread-safe. I understand that. But what I'm not clear on is what about instance variables of new'ed POJ classes? If my servlet instantiates a class containing instance variables, are those instance variables thread-safe? jd
Bear Bibeault
Author and ninkuma
Marshal

Joined: Jan 10, 2002
Posts: 63198
    
  69

Yes, unless you do something like store a reference to them in a servlet instance variable.

When you instantiate an object and store it in a thread-safe reference, such as a method-local variable, other threads have no way to "get at" the instance. Ergo, thread-safe.
[ October 19, 2006: Message edited by: Bear Bibeault ]

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John Daniel
Greenhorn

Joined: Mar 27, 2005
Posts: 20
Thank you, that's what I wanted to know. jd
 
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