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).]