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Constructors

Hama Kamal
Ranch Hand

Joined: May 29, 2011
Posts: 144

hi guys,,

in the SCJP6 book ,,,( by katy and bert ) >>>>page 133 >> rules for constructors:
i dont get the following two points could any one expalin it more with giving simple illustrating example for each!

1-Only static variables and methods can be accessed as part of the call to super()
or this(). (Example: super(Animal.NAME) is OK, because NAME is
declared as a static variable.)
2-You cannot make a call to an instance method, or access an instance variable,
until after the super constructor runs.


``Worry does not empty tomorrow of its sorrow; it empties today of its strength.''
Abimaran Kugathasan
Ranch Hand

Joined: Nov 04, 2009
Posts: 2066

Hama Kamal wrote:hi guys,,

in the SCJP6 book ,,,( by katy and bert ) >>>>page 133 >> rules for constructors:
i dont get the following two points could any one expalin it more with giving simple illustrating example for each!

1-Only static variables and methods can be accessed as part of the call to super()
or this(). (Example: super(Animal.NAME) is OK, because NAME is
declared as a static variable.)
2-You cannot make a call to an instance method, or access an instance variable,
until after the super constructor runs.


Please UseRealWords! Before creating an object, how can you access it's instance variables?


|BSc in Electronic Eng| |SCJP 6.0 91%| |SCWCD 5 92%|
Stephan van Hulst
Bartender

Joined: Sep 20, 2010
Posts: 3615
    
  14

I don't see many spelling mistakes, just one small typo. Please carry on with the subject, guys.
Hama Kamal
Ranch Hand

Joined: May 29, 2011
Posts: 144

many thanks however, i have one more question,, if it happens in a constructor to have call to both super and this ,, which one comes first?
Stephan van Hulst
Bartender

Joined: Sep 20, 2010
Posts: 3615
    
  14

You can't use both super() and this() in a constructor, only one of the two.
 
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subject: Constructors