Super class for all the classes in java
posted 20 years ago
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which is the super class for java Language...
this is an interview question .
I SAY Object is the super class for java Language ...
then he asked whether object class will extend ??
i say Yes it will implectly extend ...
then he whether each and every class will extend object
i say yes ...
then he asked multiple inheritance is possible in java ...
i say no ...
then how will say object class will extend in each and every class....
hai friends if there is any solution tell mem
by
dhana
this is an interview question .
I SAY Object is the super class for java Language ...
then he asked whether object class will extend ??
i say Yes it will implectly extend ...
then he whether each and every class will extend object
i say yes ...
then he asked multiple inheritance is possible in java ...
i say no ...
then how will say object class will extend in each and every class....
hai friends if there is any solution tell mem
by
dhana
posted 20 years ago
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Hi,
When you create a subclass like,
class child extends parent this means child is not the direct subclass of class Object, "child" is the sub class of "parent" and "parent" is a subclass of "Object" .. So this means that child is also an "Object" and it doesn't means that it's multiple inheritance it's only single inheritance.
If you are C++ programmer you can say
class child : public parent1,public parent2 ( i'm sorry if the above C++ syntax is wrong ). This piece of code says that child has all the non private members of parent1 & parent2 directly inherited this is multiple inheritance.
PS: Please check your display name before a bartender catches you!!
When you create a subclass like,
class child extends parent this means child is not the direct subclass of class Object, "child" is the sub class of "parent" and "parent" is a subclass of "Object" .. So this means that child is also an "Object" and it doesn't means that it's multiple inheritance it's only single inheritance.
If you are C++ programmer you can say
class child : public parent1,public parent2 ( i'm sorry if the above C++ syntax is wrong ). This piece of code says that child has all the non private members of parent1 & parent2 directly inherited this is multiple inheritance.
PS: Please check your display name before a bartender catches you!!
Thanks & regards, Srini
MCP, SCJP-1.4, NCFM (Financial Markets), Oracle 9i - SQL ( 1Z0-007 ), ITIL Certified
Srinivasa Raghavan
Ranch Hand
Posts: 1228
posted 20 years ago
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Hi the Signature of Object Class is
public class java.lang.Object then what do you mean by these lines ?
public class java.lang.Object then what do you mean by these lines ?
then he asked whether object class will extend ??
i say Yes it will implectly extend ...
Thanks & regards, Srini
MCP, SCJP-1.4, NCFM (Financial Markets), Oracle 9i - SQL ( 1Z0-007 ), ITIL Certified
dhana sss
Greenhorn
Posts: 16
posted 20 years ago
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hai friends ,,
am asking .. there is one class
class test
{
public static void main(String arg[])
{
System.out.println("whether this class will extends public class java.lang.Object");
}
}
am asking .. there is one class
class test
{
public static void main(String arg[])
{
System.out.println("whether this class will extends public class java.lang.Object");
}
}
Srinivasa Raghavan
Ranch Hand
Posts: 1228
posted 20 years ago
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Obviously it has to.
Execute this piece of code.
You can see true in the console.
[ March 21, 2005: Message edited by: Srinivasa Raghavan ]
Execute this piece of code.
You can see true in the console.
[ March 21, 2005: Message edited by: Srinivasa Raghavan ]
Thanks & regards, Srini
MCP, SCJP-1.4, NCFM (Financial Markets), Oracle 9i - SQL ( 1Z0-007 ), ITIL Certified
dhana sss
Greenhorn
Posts: 16
posted 20 years ago
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then u'r saying that all the classes will extend Object Class ...
am i right ...
tell me "srini"
by
dhana
am i right ...
tell me "srini"
by
dhana
posted 20 years ago
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All classes extend Object in one of three ways:
1.
class A extends Object {...} // Object is the direct superclass
2.
class A {...} // Object is still the direct superclass
3.
class X {...}
class A extends X {...} // Object is an indirect superclass
Every class's constructors chain up to eventually call the Object no-arg constructor and every class inherits Object's methods like equals(), finalize(), and hashcode().
1.
class A extends Object {...} // Object is the direct superclass
2.
class A {...} // Object is still the direct superclass
3.
class X {...}
class A extends X {...} // Object is an indirect superclass
Every class's constructors chain up to eventually call the Object no-arg constructor and every class inherits Object's methods like equals(), finalize(), and hashcode().
Mike Gershman
SCJP 1.4, SCWCD in process
dhana sss
Greenhorn
Posts: 16
posted 20 years ago
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is there any difference between implicit and explicit class
if any tell me ...
by
dhana
if any tell me ...
by
dhana
Srinivasa Raghavan
Ranch Hand
Posts: 1228
posted 20 years ago
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Hi,
What do you mean by "implicit and explicit class" ?
What do you mean by "implicit and explicit class" ?
Thanks & regards, Srini
MCP, SCJP-1.4, NCFM (Financial Markets), Oracle 9i - SQL ( 1Z0-007 ), ITIL Certified
dhana sss
Greenhorn
Posts: 16
posted 20 years ago
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i do no u only say A class extend Explicitly and object class will extend Implicitly .....
by
dhana
by
dhana
posted 20 years ago
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The master of all classes in java plus the one you create every day.
Java does support multiple inheritance, right. But how ? that is through
implimentation of interfaces. Unlike c++, you can't do the following in java.
class Sub extends Super,Object{};
But implicitely, every class created in java extends Object.
that why you inherit some methods like wait(), toString ....
from class Object. eg
class Tricky{} // implicitly = the compiler sees class Tricky extends Object
class BeNice extends Tricky {}
// what you have is what you typed, there isn't a direct call to Object
// by BeNice class but it extends Object through inheritance.
Wao , hope it helps
Java does support multiple inheritance, right. But how ? that is through
implimentation of interfaces. Unlike c++, you can't do the following in java.
class Sub extends Super,Object{};
But implicitely, every class created in java extends Object.
that why you inherit some methods like wait(), toString ....
from class Object. eg
class Tricky{} // implicitly = the compiler sees class Tricky extends Object
class BeNice extends Tricky {}
// what you have is what you typed, there isn't a direct call to Object
// by BeNice class but it extends Object through inheritance.
Wao , hope it helps
SCJA(Beta) SCJP 1.4 SCWCD 1.4 SCBCD 1.3 SCBCD 5.0 beta <br />The more practice we get, the better we are at the exams and in life in general. Pls join me at My DEN.
posted 20 years ago
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All classes directly or indirectly inherit from java.lang.Object, with one exception.
All classes have one, and only one, superclass, with one exception.
The exception is both cases is for java.lang.Object itself.
All classes have one, and only one, superclass, with one exception.
The exception is both cases is for java.lang.Object itself.
Tony Morris
Java Q&A (FAQ, Trivia)
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