Ramamoorthy Periasamy

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since Feb 06, 2006
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Recent posts by Ramamoorthy Periasamy

I actually figured out the problem. Thanks anyway
As far as I heard yeah we can override all the annotations with Deployment descriptor
I've defined the Inheritance strategy as InheritanceType.JOINED and got the entity class Vehicle and Truck extends Vehicle. I am using the derby database and have the tables created.

Vehicle has id(pk), name, wheels columns and Truck has id(fk), chase columns

When I try to persist these objects I am getting below exception. Please advice

Exception [TOPLINK-4002] (Oracle TopLink Essentials - 2006.8 (Build 060830)): oracle.toplink.essentials.exceptions.DatabaseException
Internal Exception: org.apache.derby.client.am.SqlException: 'DTYPE' is not a column in table or VTI 'APP.VEHICLE'.Error Code: -1
Call:INSERT INTO VEHICLE (ID, WHEELS, NAME, DTYPE) VALUES (?, ?, ?, ?)
bind => [1493225404, 4, GMC Truck 1, Truck]
Query:InsertObjectQuery(com.fruit.persistance.Truck@f30c34)
Hi All,

Last friday I cleared the exam. scored 80%. questions posted in forums were useful. thanks a lot.

Ram
15 years ago


Can you please help me out how to do Arrays.sort()? I am getting runtime exception. Did I miss anything in the code. Please advice
Thanks

I declared an instance enum with private/protected access modifier, The compiler did not flag any error. Whereas in the chapter one its mentioned that enums can only have public and default access. Can any one please clear my confusion?



If the enum declared out outside class then it should have only public or default access. Whereas, if the enum declared inside class then it may have private and protected too
may be you can use List<? extends String> l = aList;
instead of List<? extends Object> l = aList;

to have more fun add below code in the main method and see the output


When you change the above boolean variable b to final, then code wont compile, it says unreachable code after while.

This is because when the compiler knows the condition is false for sure (In this case we used final variable b which is compile time constant)then it will simply says anything after that statement are unreachable.
Yes. When you use return or throw in finally block it will show a warning message called "finally block does not complete normally".

Always remember before printing the RuntimeException it executes the finally block (if anything defined). In this case since we had the return statement in finally compiler didnt get a chance to print the RuntimeException!

Originally posted by Rushikesh Wagh:
I Wondered How Hell this Code Gets Compiled
class testing{
protected void finalize(){
System.out.println("Object GCd");
}
void nothing(){
String s2 = new String("Susan");
s1=null;
System.gc();
}
public static void main(String args[]){
testing t = new testing();t.nothing();
}
}

What is s1???




I guess that was the typo error. read it as s2 = null


class Bar might have declared as abstract to be more appropriate. Then only its a worth creating a anonymous class (which is a subclass of Bar).
Thats what you need to understand the difference between method invocation conversion and assignment conversion.

Assignment conversion includes the narrowing primitive conversions.
example: short s = 10; // no error
Method invocation conversion doesn't include the narrowing primitive conversions
example: method(short s) {} method(10); // compile time error
try this