self dot mean code example

Example: Create a Point class with attributes that represent X and Y coordinates. Create a printXY method that prints information (X and Y) in the form ((45, 56)).

/**
 * The LineSub class, subclass of Point.
 * It inherits the begin point from the superclass, and adds an end point.
 */
public class LineSub extends Point {  // Inherited the begin point
   // Private instance variables
   Point end;   // Declare end as instance of Point
 
   /** Constructs a LineSub instance with 2 points at (x1, y1) and (x2, y2) */
   public LineSub(int x1, int y1, int x2, int y2) {
      super(x1, y1);
      this.end = new Point(x2, y2);   // Construct Point instances
   }
   /** Constructs a LineSub instance with the 2 given Point instances */
   public LineSub(Point begin, Point end) {
      super(begin.getX(), begin.getY());  // Need to construct super
      this.end = end;
   }

   // Getters and Setters 
   public Point getBegin() {
      return this;   // upcast to Point (polymorphism - to be discussed later)
   }
   public Point getEnd() {
      return end;
   }
   public void setBegin(Point begin) {
      super.setX(begin.getX());
      super.setY(begin.getY());
   }
   public void setEnd(Point end) {
      this.end = end;
   }
 
   // Other Get and Set methods
   public int getBeginX() {
      return super.getX();  // inherited, super is optional
   }
   public void setBeginX(int x) {
      super.setX(x);        // inherited, super is optional
   }
   public int getBeginY() {
      return super.getY();
   }
   public void setBeginY(int y) {
      super.setY(y);
   }
   public int[] getBeginXY() {
      return super.getXY();
   }
   public void setBeginXY(int x, int y) {
      super.setXY(x, y);
   }
   public int getEndX() {
      return end.getX();
   }
   public void setEndX(int x) {
      end.setX(x);
   }
   public int getEndY() {
      return end.getY();
   }
   public void setEndY(int y) {
      end.setY(y);
   }
   public int[] getEndXY() {
      return end.getXY();
   }
   public void setEndXY(int x, int y) {
      end.setXY(x, y);
   }
 
   /** Returns a self-descriptive string */
   public String toString() {
      return "LineSub[begin=" + super.toString() + ",end=" + end + "]";
   }
 
   /** Returns the length of this line */
   public double getLength() {
      return super.distance(end);
   }
}