General Java Questions III

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 General Java Questions III

Q: I propose that Java should allow multiple inheritance if...

Everyone knows the potential problem with multiple inheritance is when you run into

the problem of having two instances of a grand parent super class.

For example:

class A extends D {int i; }

class B extends D {int i; }

class C extends A,B {}

Potentially, you could have two copies of D for each instance of C.

However, I propose that Java should allow multiple inheritance if there are no

instance variables associated with the abstracts that the base class is extending.

abstract class A { public setX(); public setY(); public setAll() {setX (); setY(); }

abstract class B { public setC(); public setD(); public setBoth()

{setC(); setD(); }

class C extends A,B {}

You won t have two instances of some grandfather class, since A and B doesn t have

instances variables.

I hope the next versions of Java explores this issue.

Answer: It does. They re called interfaces:

interface A { public void setX(); public void setY(); public void setAll(); }

interface B { public void setC(); public void setD(); public void setBoth(); }

interface C extends A,B {};

public abstract class D implements C {

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