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javasuper

Require override of method to call super


I want that when a child class overrides a method in a parent class, the super.method() is called in that child method.

Is there any way to check this at compile time?
If not, how would I go about throwing a runtime exception when this happens?


Solution

  • There's no way to require this directly. What you can do, however, is something like:

    public class MySuperclass {
        public final void myExposedInterface() {
            //do the things you always want to have happen here
    
            overridableInterface();
        }
    
        protected void overridableInterface() {
            //superclass implemention does nothing
        }
    }
    
    public class MySubclass extends MySuperclass {
        @Override
        protected void overridableInterface() {
            System.out.println("Subclass-specific code goes here");
        }
    }
    

    This provides an internal interface-point that subclasses can use to add custom behavior to the public myExposedInterface() method, while ensuring that the superclass behavior is always executed no matter what the subclass does.