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Doubt about wrapper classes

suneetha75
Greenhorn

Joined: Feb 08, 2001
Posts: 8
Can anybody tell me Is wrapper classes are included in the SCJP
exam?
one more thing, I want to KNow some thing about the keyword Transient, How we can use it? What is the use?
Thank you
Sunee
Kathy Rogers
Ranch Hand

Joined: Aug 04, 2000
Posts: 103
Wrapper classes are included in the SCJP exam.
The transient keyword is used with serialization. You can serialize objects to transmit them in streams but when you do this, there may be sensitive class data that you don't want to transmit - for example, if you have a User object which has several attributes (name, password, age, address), you may not want to transmit the password for security reasons - you use the transient keyword to identify that data which is not included in an object's serialization. So you might declare password
private transient String password;
to indicate that it shouldn't be serialised.
Hope this helps,
Kathy
[This message has been edited by Kathy Rogers (edited February 08, 2001).]
Shrini Kulkarni
Ranch Hand

Joined: Jan 12, 2001
Posts: 63
There is also one more aspect of transient key word. This is deals with Threads. A piece of transient data - tells compiler that several threads may be accessing it simulatneously. Hence data should be completely refershed everytime from memory and completely stored back after each access.
This is generally not mentioned while mentioning about transient data.
Hope this helps
Shrinivas


Sun Certified programmer for Java2 platform.<BR>Shri_mk@hotmail.com
Angela Poynton
Ranch Hand

Joined: Mar 02, 2000
Posts: 3143
I'm moving the to Programmers Certification Study!


Pounding at a thick stone wall won't move it, sometimes, you need to step back to see the way around.
Sowmya Vinay
Greenhorn

Joined: Feb 01, 2001
Posts: 24
Originally posted by Shrini Kulkarni:
There is also one more aspect of transient key word. This is deals with Threads. A piece of transient data - tells compiler that several threads may be accessing it simulatneously. Hence data should be completely refershed everytime from memory and completely stored back after each access.
This is generally not mentioned while mentioning about transient data.
Hope this helps
Shrinivas

I think what you are referring to is volatile keyword.The only transient keyword I know, makes the variables , not to be saved during serialization.
Please correct me if I am wrong!
Sowmya Vinay

[This message has been edited by Sowmya Vinay (edited February 12, 2001).]
 
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