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Accessing subclass methods  RSS feed

shalaka wadekar
Ranch Hand
Posts: 37
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Hi All,

I am in a sorrowful state. Please help me.

I am developing a sample code for my application. In my handler class, I have an object of another class. Now using this object I made a call on its method. This method returned an an abstract class. Now what I actually want is to call a method of a subclass of this abstract class. What do I do? Please suggest.

To quote an example, its something like this:

This is what I have so far. Now what I want is to call a method of the subclass of absclass from my handler class. How do I achieve this. Please help.

Ernest Friedman-Hill
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If the method is declared in the abstract class, then just call the method on the abstract class reference; the subclass's implementation will be called. This is really the whole point of abstract classes.

If, on the other hand, the method is only declared in the subclass, then the only way to call the method directly is to cast the abstract class reference to the subclass, and call the method on the casted value; i.e.,

SubClass1 s1 = (SubClass1) b1;

- or -

((SubClass1) b1).subclassMethod();

Of course, this will fail at runtime if b1 is not an instance of SubClass, but is in fact an instance of some other subclass of absclass; therefore it's generally a bad idea. If this is what's going on, then you should back up a little, describe the problem you're trying to solve, and we can help you design your classes better.
It is sorta covered in the JavaRanch Style Guide.
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