Java base class and sub class methods override [closed]

StackOverflow https://stackoverflow.com/questions/19712595

  •  02-07-2022
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Question

I am new to Java programming, but have some basic understanding. Here is my question, i have a base class and many classes extends this base class. In some cases, after a standard action performed by the base class method , i need to do some action only for some sub classes. So i just done as in the following way. Just want to check i am right as per OOPS

class BaseClass {

    public void deleteThisRecord() {
        // All standard code goes here
        doSomethingAfterDelete(); // call clean up method after sucessful delete
    }   

    public void doSomethingAfterDelete() {
        // Nothing is here, let the sub class override this if there is need
    }
}

class OneClass extends BaseClass {
    // other methods

    @Override
    public void doSomethingAfterDelete() {
        // do some action after delete
    }
}
Was it helpful?

Solution

Yes, this will work in the way that you describe, in that derived classes can choose to implement doSomethingAfterDelete() or not. However, in Java, all methods of a base class can be overridden by default in the derived class, so you may like to add the final modifier to your method deleteThisRecord() to prevent it being overridden:

public final void deleteThisRecord() {
    // All standard code goes here
    doSomethingAfterDelete(); // call clean up method after successful delete
}

OTHER TIPS

Abstract methods are placeholder methods that can only be called from the subclass. I suggest that if doSomethingAfterDelete() is an empty placeholder method intended to be overridden, you should write it as:

public abstract void doSomethingAfterDelete();

and then in the subclass, override it.

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