用Java初始化ivars

Question

Is there a difference or preferred preference between declaring and setting the default ivars like so:

public class Foo
{
   private int yes = 0;
   private String name = "";

   //...
   //constructors, setters, getters, etc.
}

---

public class Foo
    {
       private int yes;
       private String name;

       public Foo()
       {
          yes = 0;
          name = "";
       }
       //...
       //setters, getters, etc.
    }

Also, in constructors and other methods in Foo should I be setting and getting the ivars with the accessor and mutator methods or with simply assigning them directly?

Answer 1

primitive types ( int in your case) are initialized by default values automatically, so there no reason to explicitly set it to 0 ;

What about Strings and other objects: it's completely depends on your preferences. I prefer not to initialize it in constructor. But keep in mind that in case of initilizing fields in constructor you can handle exceptions if field initializing throws some exception

Answer 2

Same thing. Accessor and mutators methods will be needed for external classes.

Answer 3

It doesn't matter and it's basically personal preference. Java compiler copies the initialization from a class to every constructor (no extra calls, it's really a direct copy in the bytecode).

Personally, I prefer to put the data-independent initialization to the class while I put the data that might depend on the constructor parameters to the constructor itself.