I need to create a base class that implements several interfaces with lots of methods, example below.
Is there an easier way to delegate these method calls without having to create a horde of duplicate methods?
public class MultipleInterfaces implements InterFaceOne, InterFaceTwo { private InterFaceOne if1; private InterFaceTwo if2; public MultipleInterfaces() { if1 = new ImplementingClassOne(); if2 = new ImplementingClassTwo(); } @Override public void classOneMethodOne { if1.methodOne(); } @Override public void classOneMethodTwo { if1.methodTwo(); } /** Etc. */ @Override public void classTwoMethodOne { if2.methodOne(); } @Override public void classTwoMethodTwo { if2.methodTwo(); } /** Etc. */ }
Your class can implement more than one interface, so the implements keyword is followed by a comma-separated list of the interfaces implemented by the class. By convention, the implements clause follows the extends clause, if there is one.
One of the core principles of Object-Oriented Programming – inheritance – enables us to reuse existing code or extend an existing type. Simply put, in Java, a class can inherit another class and multiple interfaces, while an interface can inherit other interfaces.
Yes, we can do it. An interface can extend multiple interfaces in Java.
As said, there's no way. However, a bit decent IDE can autogenerate delegate methods. For example Eclipse can do. First setup a template:
public class MultipleInterfaces implements InterFaceOne, InterFaceTwo { private InterFaceOne if1; private InterFaceTwo if2; }
then rightclick, choose Source > Generate Delegate Methods and tick the both if1
and if2
fields and click OK.
See also the following screens:
There is one way to implement multiple interface.
Just extend one interface from another or create interface that extends predefined interface Ex:
public interface PlnRow_CallBack extends OnDateSetListener { public void Plan_Removed(); public BaseDB getDB(); }
now we have interface that extends another interface to use in out class just use this new interface who implements two or more interfaces
public class Calculator extends FragmentActivity implements PlnRow_CallBack { @Override public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) { } @Override public void Plan_Removed() { } @Override public BaseDB getDB() { } }
hope this helps
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