Java：通过使用最终的设置方法避免警告“构造函数中的可重写方法调用”

Question

I always used setters as a place to validate a value before assigning it to a field.

public class Person {
    private int id;

    public int getId() {
        return this.id;
    }

    public int setId(int id) {
        if (id < 0) {
            throw new IllegalArgumentException("id must be positive.");
        }
        this.id = id;
    }

    public Person(int id) {
        setId(id);
    }
}

What I think is good about it is that I now have one place where a value gets validated before assignment and I can call it from everywhere. But the compiler warns me about that overridable method call in the constructor of the class. I read What's wrong with overridable method calls in constructors? and understand the issues this might cause and that it is recommended to use a Builder Pattern instead. But would it be also okay to just add final to the getters and setters instead to prevent overriding those properties?

Answer 1

would it be also okay to just add final to the getters and setters instead to prevent overriding those methods?

Yes, it would. In addition to stopping the warning, it would make your code more robust, because subclasses would not be able to change the validation in your setters, either on purpose or by accident.

Another solution would be to make a private method for validating the data, and call it from both the constructor and the setter. This would solve the problem as well:

private void setIdChecked(int id) {
    if (id < 0) {
        throw new IllegalArgumentException("id must be a positive.");
    }
    this.id = id;
}
public void setId(int id) {
    setIdChecked(id);
}
public Person(int id) {
    setIdChecked(id);
}