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Why constructor didn't execute?  RSS feed

 
Dana Ucaed
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Hi,

I learned for exam OCA 7.
Please help me: don't understand why constructor of class SubAlpha don't execute:



and 

Thank you
 
Hardik Nai
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I am checked and founded class Chapter2_11 main called own constructor.
Rule of inheritance called super class constructor like Alpha.
SubAlpha class haven't any relationship  to  Chapter2_11.
 
Ganesh Patekar
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Welcome to CodeRanch Anda!!    As you are new, I've put code tags around your code, see It looks nice now with code tags. Please refer ( click here --->) Use Code Tags to know how to use code tag. Aways quote the source click here --->  Quote Your Sources
 
Ganesh Patekar
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Anda Cristea wrote:Please help me: don't understand why constructor of class SubAlpha don't execute:
When you create an object of a class, If that class extends another class then constructor of super class(If this superclass has another super çlass then constructor of super of this super class like that..) first gets executed then subclass's constructor.

In your example, Chapter2_11 extends Alpha so superclass of Chapter2_11 is Alpha but not SubApha (Note: a class can extend only one class). When you create an object of Chapter2_11 then first constructor of superclass of Chapter2_11 i.e. constructor of Alpha gets executed then constructor of Chapter2_11.

Chapter2_11 doesn't extend SubAlpha so constructor of SubAlpha doesn't execute.

Example 1:
Output:
Constructor of class One executed
Constructor of class Two executed
Constructor of class Three executed

In above example 1 you can see the constructor of superclass's gets executed first then subclass's ...
 
Dana Ucaed
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Hardik Nai wrote:I am checked and founded class Chapter2_11 main called own constructor.
Rule of inheritance called super class constructor like Alpha.
SubAlpha class haven't any relationship  to  Chapter2_11.


I realised the solution after you posted this question.
 
It is sorta covered in the JavaRanch Style Guide.
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