Properties/Methods of Parent Class not available to Child Class?

[doni49]

Given the following code, why is "NextKey" not available to methods in MyClass2?

I always thought that when you extend a class, all of the member methods and properties would be part of the second class--otherwise, what's the point of extending an existing class?

class MyClass1{
  public int getNextKey(){
    return _NextKey;
  }
  public void setNextKey(int val){
    _NextKey = val;
  }
  MyClass1(){
  }
  private int _NextKey;
}

class MyClass2 extends MyClass1{
  MyClass2(){
    super();
  }
  public void doSomething(value){
    _NextKey = value;
  }
}

[hrbuckley]

Originally Posted by doni49

Given the following code, why is "NextKey" not available to methods in MyClass2?

I always thought that when you extend a class, all of the member methods and properties would be part of the second class--otherwise, what's the point of extending an existing class?

Try:

class MyClass1{
  public int getNextKey(){
    return _NextKey;
  }
  public void setNextKey(int val){
    _NextKey = val;
  }
  MyClass1(){
  }
  protected int _NextKey;
}

class MyClass2 extends MyClass1{
  MyClass2(){
    super();
  }
  public void doSomething(int value){
    _NextKey = value;
  }
}

[doni49]

HRB,

Thanks for that. After posting this, I found a tutorial on Sun's web site that talks about protected vs private. I'll use protected, but the reason I was TRYING to use private is that I've got other classes in the same file and I didn't want those other classes to use the other classes to have access to these properties/mthods.

I really thought that "extending" a class copied the class as sort of a starting point and that you just added new stuff or override stuff in the parent.

Oh well.

[hrbuckley]

All object oriented languages I've used observe the same semantics, private: avaialble to no other classes, public: available to all other classes, protected: private except for "children" for which it is public.