Re: question about the toString Method

Art Cummings wrote:


     First, println() is not one method but a whole family of
methods of the PrintStream class. There's a println() method
that takes an int argument, another that takes a double, yet
another that takes no argument at all. The particular one
you're calling is the println() that takes an Object.

     So, what does the println(Object) method of PrintStreamClass
do? First thing, right off the bat, is it calls the static
String.valueOf() method on the same object, and from that it
gets a String which it then prints. Like println() itself,
String.valueOf() has many versions for many argument types, and
the one we wind up with is String.valueOf(Object).

     Over to the String class; what does String.valueOf(Object)
do? It depends: If the argument is null it just returns the
four-character String "null". Otherwise -- ta-daaah! -- it
calls the object's own toString() method to get a String, and
that's where the call to Course's toString() method comes from:

    You call
       System.out.println(myCourse), which calls
          String.valueOf(myCourse), which calls
             myCourse.toString(), which returns a String to
          String.valueOf(myCourse), which returns the same String to
       System.out.println(myCourse), which then calls
          System.out.print(theString), which returns to
       System.out.println(myCourse), which eventually returns to
    You.

--
Eric Sosman
esosman@ieee-dot-org.invalid