Extending Classes and Inheritance - Beginning Java - page 315

str.append(" "+ nextPoint); // Output the

current point
nextPoint = nextPoint.getNext(); // Make the next

point current
}
return str.toString();

}

private ListPoint start; // First ListPoint

in the list
private ListPoint end; // Last ListPoint in

the list
}

Directory "TryPolyLine"

This source file also goes in the TryPolyLine directory.
You might want to be able to add a point to the list by specifying a coordinate pair. You could overload
the addPoint() method to do this:

// Add a point defined by a coordinate pair to the list
public void addPoint(double x, double y) {
addPoint(new Point(x, y));

}

Directory "TryPolyLine"

You just created a new Point object in the expression that is the argument to the other version of ad-
dPoint() .
You might also want to create a PolyLine object from an array of coordinates. The constructor to do this
would be:

// Construct a polyline from an array of coordinates
public PolyLine(double[][] coords) {
if(coords != null) {
for(int i = 0; i < coords.length ; ++i) {
addPoint(coords[i][0], coords[i][1]);

}

}

}