/*             Methods that Return Values 


    You should recall the difference between the following lines:

    JOptionPane.showMessageDialog(null,"hello");
    s = JOptionPane.showInputDialog(null,"prompt: ");  // s a String variable

    The first line invokes the "showMessageDialog" method of a server
called JOptionPane.  null and "hello" are "parameters" which I'll
explain later.  The difference to note here is that showMessageDialog
is method that can stand alone as a statement, whereas showInputDialog
can not.  showMessageDialog is a function that returns no value (like
the functions of our previous example).  showInputDialog returns a
value - a String value.  And thus calls to showInputDialog are
expressions, not statements (until you do something else with it, like
assigning the String returned to a variable).

    We can write functions that return values by replacing "void" with
the type of value it will return.  To return a value from inside a function,
we introduce the special statement 

    return x;
    
    Which will cause the function executing this code to return the value x,
whatever it might be.  For example, we can define a method (inside some class)
with

public int f()
{ return 3; } 

or 

pubic String g()
{
  return "hello";
}

Now when we call these functions, the functions calls must be treated as
expressions as opposed to stand-alone values!  That is, you can nolonger
just say "myobject.f();"  You must do something with the integer value
returned by f, for example:

int x;
x = myobject.f();  

                   IMPORTANT ENOUGH TO EMPHASIZE:

If a function is declared void, that means it can't return a value so
don't use "return" anywhere.  If a function is declared to return a
value, such as of type int, then you must execute a return statement
before exiting a function.  For example, if you have an if-else
statement as the last statement of your function, then both the if and
else components must end by a return statement.  Don't get fixated
with the syntax - THINK!  That is, think about whether you really want
your function to return something or not before puting return
statements all over the place.  Most mistakes made by beginners are
caused by them not thinking clearly first before they start to write
code.

In our next major example, we rewrite the waiter class to illustrate
functions that return values.  In addition to a monolithic menu()
function, I (the client) may want to know the price of individual
items.  Furthermore, I don't necessarily just want these values
printed.  I may decide to do some calculation with it, or I may want
to display it on some fancy graphical interface.  It's a general
principle of computer science to only do I/O when you have to.

*/



/*  Class with functions that take no parameters but return values*/

class waiter
{

// services are defined in the form of methods (functions):

 public void water()
    {
	System.out.println("We don't have water!");
    }

 public void check()
    {
	System.out.println("Here's your check. Pay up!");
    }

 // ... other methods such as menu() omitted for brevity

 public double priceofchicken()
    {
	return 5.95;
    }

 public double priceofburger()
    {
	return 4.95;
    }

 public double priceoffries()
    {
	return 1.95;
    }

} // end of class waiter



public class objects1
{

 public static void main(String[] args)
    {
	waiter ourwaiter; // declares a waiter variable
	ourwaiter = new waiter();  // assigns variable a waiter object
	double x;   // variable to hold price of burger
	double y;   // variable to hold price of chicken

	x = ourwaiter.priceofburger();  // assign x and y to values returned
	y = ourwaiter.priceofchicken(); // by function calls.

	if (x<y) // buy cheaper product
	    { System.out.println("I'll take the burger 'cause it's cheaper"); }
	else
	    { System.out.println("I'll take the chicken."); }

	ourwaiter.check();  
    } // main

} // class objects1


/*  
    You might be asking, why do we have to define three different
functions to return the prices of the items?  It's indeed possible to
combine the three "priceof-" functions into one.  But then we have to
come up with another way for the caller (client) to specify if he or
she is looking for the price of burgers, chicken or fries.  This is
accomplished by having functions take PARAMETERS!  Stay tuned ...
First you have to understand what we've already covered.  

Repeat the following to yourself 1000 times:

   FUNCTIONS THAT RETURN VALUES ARE EXPRESSIONS

   FUNCTIONS THAT RETURN NO VALUES ARE STATEMENTS
*/