Random Walking Program

Question

I'm to write a program that does the following

'We will assume that the random walk takes place on a square grid with the point (0,0) at the center. The boundary of the square will be a single integer that represents the maximum x and y coordinate for the current position on the square (so for a boundary value of 10, both the x and y coordinates can vary from -10 to 10, inclusive). Each step will be one unit up, one unit down, one unit to the left, or one unit to the right. (No diagonal movement.)'

The RandomWalk class will have the following instance data (all type int): • the x coordinate of the current position • the y coordinate of the current position • the maximum number of steps in the walk • the number of steps taken so far in the walk • the boundary of the square (a positive integer -- the x and y coordinates of the position can vary between plus and minus this value)

First declare the instance data (as described above) and add the following two constructors and toString method.

a)RandomWalk (int max, int edge) - Initializes the RandomWalk object. The maximum number of steps and the boundary are given by the parameters. The x and y coordinates and the number of steps taken should be set to 0.

b)RandomWalk (int max, int edge, int startX, int startY) -- Initializes the maximum number of steps, the boundary, and the starting position to those given by the parameters.

c)String toString() - returns a String containing the number of steps taken so far and the current position -- The string should look something like: Steps: 12; Position: (-3,5)

So for part 1 this is what I came up with public class RandomWalk {

int max;
int edge;
int startX;
int startY;

public RandomWalk (int max, int edge)
{
    this.max = max;
    this.edge = edge;

}

public void RandomWalk (int max, int edge, int startX, int startY)
{
    this.max = max;
    this.edge = edge;
    this.startX = startX;
    this.startY = startY;
}

public String toString()
{
    return "Max amount of steps.:" + this.max + ",," + "Edge.:" + this.edge +
            ",," + "Starting position on X.:" + this.startX + ",," + "Starting position of Y.:" + this.startY;
}

But apparently this is the test class

public static void main (String[] args)
{

    int maxSteps; // maximum number of steps in a walk
    int maxCoord; // the maximum x and y coordinate
    int x, y; // starting x and y coordinates for a walk
    Scanner scan = new Scanner(System.in);
    System.out.println ("\nRandom Walk Test Program");
    System.out.println ();
    System.out.print ("Enter the boundary for the square: ");
    maxCoord = scan.nextInt();
    System.out.print ("Enter the maximum number of steps: ");
    maxSteps = scan.nextInt();
    System.out.print ("Enter the starting x and y coordinates with " +
            "a space between: ");
    x = scan.nextInt();
    y = scan.nextInt();     
}
}

I'm not sure what the test program is supposed to be storing, I'd just like clarification on my code.

Ar there any examples one can think of that can help me go in the right direction?

What's the problem? Are you looking for [Code Review](http://codereview.stackexchange.com/)? — mwerschy, Nov 29 '14 at 21:50
Don't forget fields for "a boundary value" and "the number of steps taken so far." — trashgod, Nov 29 '14 at 22:11
@mwerschy my problem is that I dont know if I'm doing this correctly and I'm not sure how to check it. — Uri D. Charles, Nov 29 '14 at 22:17
@UriD.Charles: Oops, I see `edge` represents the boundary, but you still need a "number of steps taken so far." I've elaborated below. — trashgod, Nov 30 '14 at 05:50

score 1 · Answer 1 · edited May 23 '17 at 10:33

The term instance data refers to the values that are available to an instance of your class when one is created. They are sometimes called fields, as of a record, or attributes, as of relation. In addition to the four you have, don't forget a field for "the number of steps taken so far." All should be private to the class; all will have well-defined initial values.

private int max;
private int edge;
private int startX;
private int startY;
private int stepNumber;

You constructors look OK; main() will eventually need to create an instant of your RandomWalk class and invoke one of it's methods. For example,

RandomWalk walk = new RandomWalk(42, 100);
walk.start();

will create a new instance having 42 for max, 100 for edge and zeroes for the start coordinates.

For reference, this FleetPanel animates a typical random walk for several simulated vehicles. The field odometer of CabPanel corresponds roughly to stepNumber.

Addendum: Looking closer, I see that you have a spurious void in your second constructor, as if it were a method. Also printing walk, which invokes toString(), is an easy way to see if things are working. For example,

System.out.println(walk);

Random Walking Program

1 Answers1