How to break overridden method if it's base method fails?

neo :

I have a method called validateData in my Parent class. In my Child class I override that method adding some additional functionality. If everything is ok, I need to call method called sendData(). Here is my code in Java:

  public class Parent {

    protected int sum;
    protected double commission;

    protected void validateData() {
        if (!isSumWrittenCorrectly()) {
            return;
        }

        performData();
    }

    private boolean isSumWrittenCorrectly() {
        if (sum < 100) {
            return false;
        }

        return true;
    }


    protected void performData() {
        commission = sum * 0.02;
    }


}


class Child extends Parent {
    private String email;

    @Override
    protected void validateData() {
        super.validateData();

        if (!isEmailWrittenCorrectly()) {
            return;
        }

        performData();
    }

    @Override
    protected void performData() {
        super.performData();


        sendData(email, commission, sum);

    }
}

So, the problem is, even if sum can be incorrectly written, the performData of child class can be called anyway. How to prevent this? I had an idea that validateData needs to return boolean and in my child class I check through super keyword. But it is a bad idea I think. So, how to break overridden method if it's base method fails?

Glains :

I suggest you let your performData() check if the validation is ok, that makes it a lot easier. You might also want to make performData() public to be accessible outside the class.

public class Parent {

    protected int sum;
    protected double commission;

    protected boolean validateData() {
        return isSumWrittenCorrectly();
    }

    private boolean isSumWrittenCorrectly() {
        if (sum < 100) {
            return false;
        }
        return true;
    }

    protected void performData() {
        if(!validateData()) {
            return;
        }
        commission = sum * 0.02;
    }
}


class Child extends Parent {

    private String email;

    @Override
    protected boolean validateData() {
        if(!super.validateData()) {
            return false;
        }
        if (!isEmailWrittenCorrectly()) {
            return false;
        }
        return true;
    }

    @Override
    protected void performData() {
        super.performData();
        if(!validateData()) {
            return;
        }
        sendData(email, commission, sum);
    }
}

In the end, it might also be easier to throw an exception in case of validation failing, that will save some true false comparisions.

public class Parent {

    protected int sum;
    protected double commission;

    protected void validateData() {
        if(!isSumWrittenCorrectly()) {
            throw new IllegalArgumentException("sum is not correct");
        }
    }

    private boolean isSumWrittenCorrectly() {
        if (sum < 100) {
            return false;
        }
        return true;
    }


    protected boolean performData() {
        validateData();
        commission = sum * 0.02;
    }
}


class Child extends Parent {

    private String email;

    @Override
    protected boolean validateData() {
        super.validateData();
        if (!isEmailWrittenCorrectly()) {
            throw new IllegalArgumentException("email is not correct")
        }
    }

    @Override
    protected void performData() {
        validateData();
        super.performData();
        sendData(email, commission, sum);
    }
}