// how do objects, classes, references work?

// Scaled back Worker class:
class Worker { 
    // FIELDS of class consist of variables and methods
    
    // Instance variables:
    int id; 
    String name;

    // Constructor (special kind of method that 
    // returns address of newly
    // created object automatically!):
    Worker() { }

    // Methods:
    // $toString$ is "built-in" and prints 
    // whatever String you wish
    // when you print the reference to an object
    String toString() {
	return "Worker: "+name+", ID: "+id; 
    }
    
} // class Worker

public class Simulation {
    public static void main(String[] args) {

	// Create a new Worker object and
	// store the addres of that object in $worker1$.
	// Also called INSTANTIATING AN OBJECT/CLASS

	   Worker worker1;
	   worker1 = new Worker();

	   // you could have combined the statements into	
	   // Worker worker1 = new Worker();
	
        // Print value of reference. Make sure you comment out $toString$
        // first:

	   System.out.println(worker1);

	// Set $worker1$ instance variables. 
	// Why INSTANCE VARIABLE?
	// Each object is an instance of a class!
	// (To make variables and methods shared by 
	// all objects instantiated from same class 
	// use $static$ -- discussed later)

	   worker1.id = 123456;
	   worker1.name = "Ira";
	
	// Print description of $worker1$. Go back and 
	// remove comments on $toString$ method:	

	   System.out.println(worker1.toString()); // long method
	   System.out.println(worker1); // short-cut

	   // $toString$ is a "built-in" method that ALL classes 
	   // automatically can use -- printing a reference causes the
	   // built-in version of $toString$ to print the reference address
	   // Otherwise, if you provide code for $toString$, Java will
	   // activate the code in your $toString$.
    }

} // class Simulation