(Turtle Graphics) Modify your solution to Exercise —Turtle Graphics—to add a graphical use...

(Turtle Graphics) Modify your solution to Exercise —Turtle Graphics—to add a graphical user interface using JTextFields and JButtons. Draw lines rather than asterisks (*). When the turtle graphics program specifies a move, translate the number of positions into a number of pixels on the screen by multiplying the number of positions by 10 (or any value you choose). Implement the drawing with Java 2D API features.

Exercise

(Screen Saver with Shapes) Modify your solution to Exercise such that it uses random-number generation to choose different shapes to display. Use methods of class Graphics.

Exercise

(Screen Saver Using Timer) Package javax.swing contains a class called Timer that is capable of calling method actionPerformed of interface ActionListener at a fixed time interval (specified in milliseconds). Modify your solution to Exercise  to remove the call to repaint from method paintComponent. Declare your class to implement ActionListener. (The actionPerformed method should simply call repaint.) Declare an instance variable of type Timer called timer in your class. In the constructor for your class, write the following statements:

timer = new Timer( 1000, this );

timer.start();

This creates an instance of class Timer that will call this object’s actionPerformed method every 1000 milliseconds (i.e., every second).

Exercise

(Screen Saver) Write an application that simulates a screen saver. The application should randomly draw lines using method drawLine of class Graphics. After drawing 100 lines, the application should clear itself and start drawing lines again. To allow the program to draw continuously, place a call to repaint as the last line in method paintComponent. Do you notice any problems with this on your system?