Queries

[Anvi Dixit]

Hi All.

here is my question.

Which of the following statements are true?
1.To be overridden a method must have the same name, parameter types and return type
2.It is possible to override methods in a superclass or the same class
3.classes that are marked as final may not be extended. - true
4.an overriding method cannot have more access (be more public) than the method being overriden.

[list]As of java 1.4 option 1 is correct. what would be the statement as of java 5.0 then?

option 4 - quite confused with the terms overriding and overriden.

thanks
Anvi

[Chandra Bhatt]

Hi Anvi,

Good catch,

# As of java 1.4 option 1 is correct. what would be the statement as of java 5.0 then?
# option 4 - quite confused with the terms overriding and overriden.

With Java 5.0 the statement should be:

To be overridden a method must have the same name, parameter types and return type except covariant return allowed with Java 5.0;

Anvi, if this sort of question is asked, we will be getting clear idea from the question itself. What is required for us to understand the covariant return, Java 1.4(restriction) and 1.5(covariant).

option 4 - quite confused with the terms overriding and overriden.

True fact:

an overriding method cannot have more access (be more public) than the method being overriden. [FALSE]
See the example

class A{
void go() {} //overridden method (by sybclass B)
protected void come() {}
}
 
class B extends A{
protected void go() {} //overriding method (go is more public)
public void come(){} //come is more public 
}

B overrides the method go() with protected access (class A's go() method
has default access)
Same in the case of method come. (protected to public overriding)



Regards,
cmbhatt

[Prasanna Choudhary]

Which of the following statements are true?
1.To be overridden a method must have the same name, parameter types and return type
2.It is possible to override methods in a superclass or the same class
3.classes that are marked as final may not be extended. - true
4.an overriding method cannot have more access (be more public) than the method being overriden.

Anvi,

1. The overridden method must have the same name, parameter types. It can have the same return type or covarient types.
2. Its not possible to override methos in the same class
3. ....
4. class X{
String aMethod(){System.out.println("In Super class");}
}

class Y extends X{
private String aMethod(){System.out.println("In Super class");} //gives error as the access is restricted
}


Thanks

[Barry Gaunt]

Marcus Green's Qustion Of the Day site is based upon SCJP 5.0 now. He explains the reason as to why option 1 is no longer correct for SCJP 5.0. Did you not read the solution?

As to option 4: it would be correct if it said more private rather than more public.