Is it possible in Java to check if objects fields are null and then add default value to all those attributes?

Question

I need to make sure that no object attribute is null and add default value in case if it is null. Is there any easy way to do this, or do I have to do it manually by checkin

Answer 1

You need to manually filter input to constructors and setters. Well... you could use reflection but I wouldn't advise it. Part of the job of constructors and setters is to validate input. That can include things like:

public void setPrice(double price) {
  if (price < 0.0d) {
    throw new IllegalArgumentException("price cannot be negative " + price);
  }
  this.price = price;
}

and

public void setName(String name) {
  if (name == null) {
    throw new NullPointerException("name cannot be null");
  }
  this.name = name;
}

You could use wrapper functions for the actual check and throwing the exception.