CS 1063  Lab 7:  Random Walks

The RandomWalk Class


Hand-in Requirements

All projects and laboratories will be submitted electronically through Blackboard.  Zip up your entire lab directory to submit as the source.  (Right click on the lab folder and follow Send To > Compressed (zipped) Folder.)  The lab folder should include the following:


Simulate a random walk using a Graphics object.  Ask the user for information.

Similar to previous programs, your program should start by printing

Lab 7 written by YOURNAME


A random walk begins at a point and repeatedly takes a step in a randomly chosen direction.  In our version, the random walk will start at the center of a circle and continue until it goes outside the circle.  Each step will be randomly chosen from one pixel up, one pixel down, one pixel left, and one pixel right (this kind of random walk is called the "drunkard's walk").  Call the nextInt method on a Random object to generate an integer between 0 and 3 and map each value to one of the steps.  The random walk will be drawn on a Graphics object.  Here is an example for a circle with a radius of 100.

A random walk in a circle with radius 100

The user should be asked for the radius of the circle and the color of the circle (from at least two choices for colors).  The program should print the values that the user enters.  The program should draw the circle on a DrawingPanel that is big enough to hold the circle, leaving some space (but not a lot of space) around the circle.  Call the drawOval on your Graphics object to draw the circle.  Each step of the random walk should drawn by calling the drawLine method on your Graphics object.  To animate the walk, call the sleep method on your DrawingPanel to pause a millisecond between each step.  After the random walk is finished, the number of steps of the random walk should be printed.


This lab must have a while loop to ensure that the radius of the circle is between 50 and 400. 

This lab must have a while loop to ensure that the user selects one of the color choices.

This lab must have a while loop to continue drawing the random walk until the walk leaves the circle.


Write and use the following methods to support your random walk.

Write a boolean method to determine whether the current position of the random walk is outside the circle.  What values do you need to make this decision?  These values need to be parameters of the method.  How will you calculate the distance from the center of the circle?  You did something similar in Lab 5.

Write a boolean method to determine whether a String answer entered by the user matches a String choice for the question.

public static boolean matchesChoice(String answer, String choice)
For example, if "blue" is one of the choices for a color, then the user should be able to enter "blue", "Blue", "BLUE", "b", or "B" to answer with this color.  However, "bluish", "navyBlue", or "blueGreen" should not match.  That is,
matchesChoice("blue", "blue") should return true.
matchesChoice("Blue", "blue") should return true.
matchesChoice("B", "blue") should return true.
matchesChoice("bluish", "blue") should return false.
matchesChoice("navyBlue", "blue") should return false.
matchesChoice("blueGreen", "blue") should return false.


Your program should compile without any errors.  A program with more than one or two compile errors will likely get a zero for the whole assignment.

The following criteria will also be used to determine the grade for this assignment: