How to block call overridden method from Child

Question

For example I have two classes.

public class PActivity {
...
    @Override
    public boolean OnEventSocket(PMSocketEvent a_iEvent)
        ...
        handled = OnEventSocket(...);
    }
}

Second class:

public class PMenu extends PActivity {
    @Override
    public boolean OnEventSocket(PMSocketEvent a_iEvent)
    {
        ...
    }
}

How can I block the calling method from the second class?

Sometimes I want call the method OnEventSocket from the base class.

I have many classes like PMenu, so I have to make the change in PActivity

you can do so by `super.OnEventSocket(....)` inside the methods of the sub classes. — nits.kk, Apr 04 '17 at 13:52
Do you want to call `OnEventSocket` from the superclass using instance of a subclass? — vhula, Apr 04 '17 at 13:58
For example my android activity is in PMenu, but i do not want call method from PMenu, but from PActivity. — asus9e, Apr 04 '17 at 14:00
If you want to call method from PActivity then you need an instance of PActivity. — vhula, Apr 04 '17 at 14:08
Possible duplicate of [how to call the overridden method of superclass](http://stackoverflow.com/questions/15668032/how-to-call-the-overridden-method-of-superclass) — vhula, Apr 04 '17 at 14:10

Michael · Accepted Answer · 2017-04-04T15:45:09.193

1

I would use a kind of template method pattern.

Essentially, rather than have an overridable public method, you override a protected method which is called by the public method. This allows you to do whatever checks you need to before invoking the overridden method.

public class PActivity {
...
    public final boolean onEventSocket(args)
    {
        if (method_should_be_called)
        {
            eventSocketImpl(args);
        }
    }

    protected boolean eventSocketImpl(args)
    {
        // default behaviour
    }
}

public class PMenu extends PActivity {
    @Override
    protected boolean eventSocketImpl(args)
    {
        // overridden behaviour
    }
}

You should be able to make this work without changing any of your PMenu implementations, with two drawbacks:

You will have a public method which should be protected
You will have to keep the current method names as they are, which may be confusing.

edited Apr 04 '17 at 15:45

answered Apr 04 '17 at 14:26

Michael

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But I have I think 30 classes like PMenu, so I must change name OnEventSocket to eventSocketImpl everywhere? – asus9e Apr 05 '17 at 07:27
I want to avoid this situation – asus9e Apr 05 '17 at 07:35
@asus9e This is what I meant by my final two bullet points. You *could* keep it as it is now but that would mean your "entry point" method (my `public` one) would need to change name. Depending on how many places in the code this is called, this may be more or less work than changing all of your `PMenu`s. – Michael Apr 05 '17 at 09:04
1

Okay, I understand :) Thanks :) This function i call only once in PActivity – asus9e Apr 05 '17 at 09:22

How to block call overridden method from Child

1 Answers1