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why i cant tell it to his Father?  RSS feed

 
Shay Gaghe
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Hi
Plase take a look on this short code:

those are the compiling errors:
"TellFather.java": Error #: 310 : cannot reference variable up before superclass constructor has been called at line 12, column 37
"TellFather.java": Error #: 310 : cannot reference variable buttom before superclass constructor has been called at line 12, column 40

Can you explain why I cant do this in this way? If I can please show me how.
Thanks
Shay Gaghe
 
Manfred Leonhardt
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Hi Shay,
You can't do it that way because the Super class all Superclasses will be completed before you are initialized. What does that mean? It means that your instance variables are not available (initialized) until the SuperClass has been completely constructed. Since you are explicitly calling the super class you can't send in your instance variables because they don't exist yet! You can however, divide the chore into multiple steps. Instead of sending in up and buttom buttons into the super constructor call just set them up after the first line. For example, the code below will work.

Regards,
Manfred.
 
It is sorta covered in the JavaRanch Style Guide.
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