How to extend a class that is already extended?

Asked Mar 09 '18 at 18:47

Active Mar 09 '18 at 19:02

Viewed 419 times

I'm building a custom view for an android app. The thing is, the custom view consists of 3 arc's (horizontaly spaced out), I want to create a seperate "arc" class to reduce redundancy.

So the question is, how do I do this if I can only extend one class in Java, since the custom view class already has to extend the "view" class?

Edit: I don't have a sample of code, just the class and initial methods.

Maybe a picture could clarify it a bit? As you see, the custom view consists of three arcs that are the same.

Edit: Here is code, but I highly doubt it is of any help.

    public class Habits extends View {
    public Habits(Context context) {
        super(context);
    }

    public Habits(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public Habits(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }


}

edited Mar 09 '18 at 19:02

asked Mar 09 '18 at 18:47

B.Cakir

1

Do you have a minimum code sample? – MartinByers Mar 09 '18 at 18:50
2

You can't. You may create `interface`s or other intermediate classes. But extending multiple classes at the same time is not possible in Java. However, your question might actually be a **XY problem**. It's likely that there's a better approach if you show us your code and explain it in more detail. – Zabuzard Mar 09 '18 at 18:50
At least related, if not a duplicate: https://stackoverflow.com/q/21824402/10077 – Fred Larson Mar 09 '18 at 18:50
1

Try to use delegation instead of inheritance. – Henry Mar 09 '18 at 18:51
I updated the question to clarify it a bit. – B.Cakir Mar 09 '18 at 18:55
I agree with @Zabuza that this smells like a classic [XY Problem](http://xyproblem.info/) where you ask how to solve a specific code problem when the best solution is to use a completely different approach. – Hovercraft Full Of Eels Mar 09 '18 at 18:57
@HovercraftFullOfEels Could be very likely the case. Any suggestions? – B.Cakir Mar 09 '18 at 18:59
java does not support multiple inheritance, so you need to change your design – user902383 Mar 09 '18 at 18:59
Use composition not inheritance as has already been suggested above. – Hovercraft Full Of Eels Mar 09 '18 at 19:01
@B.Cakir hide as much as possible behind multiple interfaces, implement some interfaces and then use delegation pattern – user902383 Mar 09 '18 at 19:01
@HovercraftFullOfEels composition looks promising, – B.Cakir Mar 09 '18 at 19:04

How to extend a class that is already extended?

0 Answers0