Synchronized Keywords in Variables

[Frank]

Hi,

In the javadocs regarding many of the java.util classes, it states
that the classes are not synchronized, and suggest using the
Collections.syn chronizedX(...) methods for getting synchronized
objects. However, why couldn't one simply declare:

private synchronized LinkedList l;

and have the variable be automatically synchronized, instead of having

private List l = Collections.syn chronizedList(n ew LinkedList());

Thanks for any help,
Frank

[Nathan Zumwalt]

Re: Synchronized Keywords in Variables

You can't use the synchronized keyword in a variable declaration, only
in a method delaration. You could make your LinkedList variable
private, create a public synchronized method that "gets" the variable
and only use that method when accessing the LinkedList... it would
amount to the same thing.

-Nathan

trollybaz@hotma il.com (Frank) wrote in message news:<c45f3aca. 0310081050.4241 c33f@posting.go ogle.com>...[color=blue]
> Hi,
>
> In the javadocs regarding many of the java.util classes, it states
> that the classes are not synchronized, and suggest using the
> Collections.syn chronizedX(...) methods for getting synchronized
> objects. However, why couldn't one simply declare:
>
> private synchronized LinkedList l;
>
> and have the variable be automatically synchronized, instead of having
>
> private List l = Collections.syn chronizedList(n ew LinkedList());
>
> Thanks for any help,
> Frank[/color]

[Chris]

Re: Synchronized Keywords in Variables

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Nathan Zumwalt wrote:
[color=blue]
> You can't use the synchronized keyword in a variable declaration,
> only
> in a method delaration. You could make your LinkedList variable
> private, create a public synchronized method that "gets" the
> variable and only use that method when accessing the LinkedList...
> it would amount to the same thing.
>
> -Nathan[/color]

Hi,
Sorry, but it actually wouldn't be the same thing. I think it's really
important to realize this. The only thing this would do, is make sure
that only one thread could GET the object at a time, it would not
determine what could be done with it once gotten. For example:

- --THREAD1--
getList().add(x );

- --THREAD2--
getList().add(y );

You could have something like this happen:

- --THREAD1-- --THREAD2--
getList() WAITING
NOT SCHEDULED getList()
add() add()

This satisfies the requirement that only one thread is executing
getList() at a time, but it DOESN'T have any impact on what either
thread does with the List once it's returned.

- --
Chris
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