Thread: Exercise 98: how to write a main method with what I'm given

Here are the instructions:

 
The program below includes the expanded version of the above definition of the APPoint class. In the space provided, complete the definition of the main method — replacing the two comments by appropriate code — so that two APPoint objects are created. The first should be assigned to the variable a and should represent the point with coordinate (25.3,–6.8). The second should be assigned to the variable b and should represent the point with coordinate (–5,16.8).
 
  public class APPoint 
  { 
    private double myX; 
    private double myY; 
 
    public APPoint( double x, double y ) 
    { 
      myX = x; 
      myY = y; 
    } 
 
    public double getX()  
    { 
      return myX; 
    } 
 
    public double getY() 
    { 
      return myY; 
    } 
public static void main( String[] args )
{
  APPoint a = //...
  //...
 
  System.out.println( "a is (" + a.getX() + "," + a.getY() + ")" );
  System.out.println( "b is (" + b.getX() + "," + b.getY() + ")" );
}
  }

I have to replace the two commented lines with code with the definition of the "main" method. As always, I'm grateful for all help.

Thanks, ghostheadx

P.S. I just need a start. I could have the answer any time I wanted at the click of a button. Please remember that I have a "show solution" button, that I am purposely NOT clicking. That is because I want to be guided, as opposed to being fed the solution unless I take to long and fall behind. Nevertheless, all help appreciated.

I think yes, but I read the article you gave me and can't quite understand based on that what a constructor IS? Is it in that article? I don't see the term "constructor" in there, but thanks. Could you help explain what a constructor is and then I'll be glad to use that information? Thanks for helping.

So it's the method that creates the instance of a class? It's sort of like a special method, JUST for that class?

--- Update ---

What does this line in the article mean

" If your class has no explicit superclass, then it has an implicit superclass of Object, which does have a no-argument constructor."

I get what a superclass is. But what is an IMPLICIT superclass? Lol, I feel so stupid for asking that question. I just think knowing that word might help my understanding a little bit.

--- Update ---

I made it work. Here is my code:

 
public static void main( String[] args )
{
  APPoint a = new APPoint (25.3, -6.8);
  APPoint b = new APPoint (-5, 16.8);
 
  System.out.println( "a is (" + a.getX() + "," + a.getY() + ")" );
  System.out.println( "b is (" + b.getX() + "," + b.getY() + ")" );
}

So, it's like a method JUST FOR creating ONE type of instance. It's the blueprints for a specific object, as opposed to one in the general category, i.e. the superclass.

Alright, so a constructor automatically makes a specific type of instance of a class?

Rephrasing and rearranging the words ghostheadx used, I will simply put: A constructor is automatically called when a new instance of its class is created.

//Creating Object To The Class APPoint using new() poerator which dynamically allocates space in heap
APPoint a = new APPoint (25.3, -6.8);
//when an object is created to the class then constructor declared in the class APPoint is invoked and perform its functionality i.e a constructor is automatically invoked when an object is created to the class.Also a constructor can be invoked even multiple objects created to the class and once for each object.
APPoint b = new APPoint (-5, 16.8);