Java Reference
In-Depth Information
TRY IT OUT: The TryGeometry Class
You can exercise the two classes you have defined with the following code in the method main() :
public class TryGeometry {
public static void main(String[] args) {
// Create two points and display them
Point start = new Point(0.0, 1.0);
Point end = new Point(5.0, 6.0);
System.out.println("Points created are " + start + " and " + end);
// Create two lines and display them
Line line1 = new Line(start, end);
Line line2 = new Line(0.0, 3.0, 3.0, 0.0);
System.out.println("Lines created are " + line1 + " and " +
// Display the intersection
System.out.println("Intersection is " + line2.intersects(line1));
// Now move the end point of line1 and show the new intersection
end.move(1.0, -5.0);
System.out.println("Intersection is " + line1.intersects(line2));
Directory "Try Geometry"
Save the file in the Try Geometry directory along with the other two class files, and Line.jav a. The program produces the following output:
Points created are 0.0, 1.0 and 5.0, 6.0
Lines created are (0.0, 1.0):(5.0, 6.0) and (0.0, 3.0):(3.0, 0.0)
Intersection is 1.0, 2.0
Intersection is 1.0, 2.0
How It Works
You first create two Point objects, which you use later in the program to create the object line1 . You
then display the points using the println() method. The toString() method that you defined in the
Point class is used automatically to generate the String representation for each Point object.
After creating line1 from the two points, you use the other constructor in the Line class to create line2
from two pairs of coordinates. You then display the two lines. The toString() member of the Line
class is invoked here to create the String representation of each Line object, and this in turn calls the
toString() method in the Point class.
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