Best Practice for initialising class variables, should they be null?

Question

class Person
private String name, address;
public String getName()
return name
public void main()
Person me = new Chris()
..........loads of code........
if(me.getName==null)
do something
else
do something else
So my question is : whats the best behaviour when declaring variables? In this case should I have initialized the Strings to the empty string?
I think i need to make a decision because I'm constantly unsure if the method should return null or empty string. So i find myself doing this occasionally :
if(person.getName()==null || person.getName().equalIgnoreCase(""))
Thanks
Chris

Answer 1

I believe that when you create an object it should be 100% ready for use. That means all private member variables set to a non-null, sensible value.
You shouldn't force clients to know what's safe and what's not:
public class Person
    private String name;
    private Date birthDate;
    public static void main(String [] args)
        Person p = new Person();
        System.out.println("age: " + p.getAge());
    public Person() { // do nothing; name is null }
    public String getName() { return name; }
    public void setName(String newName) { name = newName; }
    public Date getBirthDate() { return birthDate; }
    public void setBirthDate(Date newBirthDate) { birthDate = new Date(newBirthDate.getTime()); }
    public int getAge()
        int age = 0;
        // calculating age with a null birth date will be a problem.
        return age;
}You might argue that it's perfectly reasonable to expect a user to call setters to initialize an object after it's created, but I don't like that idiom. There's no guarantee that it'll be done properly.
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