Zero checks in the constructor and in the maintenance method?

Question

This is a topic in one of our code reviews, I would like to know more.

Let's say I'm writing a service that allows me to insert a simple Person object into a database.

public class Person
{
   private String name;
   ....
}

We have a simple VerifyNotNull method throws an IllegalArgumentException.

Which route do you take and why.

Option 1:

Check the constructor of the Person object is not null, but

public Person(String name)
{
     VerifyNotNull(name);//throws illegal arg exception if name is null
     this.name = name;
}

Option 2:

Allow creation of Person with a null value, check invalid for addPerson call.

public class PersonService
{
  public void addPerson(Person personToAdd)
  {
     VerifyNotNull(personToAdd.getName());//throws illegal arg exception
     //add code
  }
}

I don't like the idea of ​​throwing exceptions in constructors. Option 2 seems right to me, I don’t know how to explain or justify it, though.

Are exceptions allowed in constructors?

Thank you for your help!

Answer 1

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Answer 2

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Answer 3

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, factory:

class Person {
    private final String name;
    private Person(String name) { // private constructor
        this.name = name;
    }
    public static Person newPerson(String name) { // factory method
        VerifyNotNull(name); // IAE not from c'tor, guaranteed check
        return new Person(name);
    }
 }

, , Builder, :

class Person {
    private final String name;
    private Person(String name) { // private constructor
        this.name = name;
    }

    /**
     * Usage: Person p = new Person.Builder(name).build();
     */
    public static class Builder {
        private final String name;
        public Builder(String name) {
            this.name = name;
        }
        public Person build() {
            VerifyNotNull(name); // IAE not from c'tor, guaranteed check
            return new Person(name);
        }
    }
}

Answer 4

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Answer 5

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Answer 6

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public class Person
{ 
    public Person()
    {
       //Nothing much here.
    }

    public static Person Create(String name)
    {
        VerifyNotNull(name);//throws illegal arg exception if name is null
        Person person = new Person();
        person.name = name;
        return person;
    }

    ...
}

Answer 7

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