Question

I have the following java-program, that creates a random walk starting at (0,0) and continuing until x or y is greater than abs(n).

First: I get an error, when I try closing the Scanner by inserting "reader.close(); " in line 28. It says "Unreachable code". How can I fix that?

Second: Is it possible to create a different colour for the StdDraw.point when it reaches a point on one of the edges "n+1" or "n-1" ?

1 import java.util.*; 3 public class RandomWalkf 4 5 public static void main(String args)I 6 Scanner readernew Scanner(System. in); System.out.print("Enter the size of grid: "); // Taking input of the size of the grid 10 do [ try int n = reader.nextInt(); if(n<= 0) { 12 13 // Saves integer entered as str 15 // Catches error if integer is negative System.out.println(n" is not a positive integer. Please enter a positive integer (0 to terminate): "); 17 18 19 20 21 else if (n > 0) walk(n); System.out.printlnC"nEnter the size of grid: "); // Makes sure the program catches strings as an error. Prints error message and clears Scanner catch (InputMismatchException e) f 23 24 25 26 27 System.out.println("Input is not an integer. Please enter a positive (0 to terminate): "; reader.nextLineO } while (true); reader.slse) ね28 29 30 31 public static void givePos(int X, int ) 32 //A function to print the position System.out, format("\nPosition-(Xd %d) ",X,Y); , 34

Answer 1

Answer First :

        You miss the else condtion in your while loop which should be execute when n = 0. 
        So when you are not using break statement for while loop then the code after while loop is unreachable.
        You should give a condition in loop after that program can be continue.
        I make this for you now reader.close() is reachable.
        
        // yout main method
        public static void main(String[] args) {

                Scanner reader = new Scanner(System.in);

                System.out.print("Enter the size of grid : ");

                do {
                        try {
                                int n = reader.nextInt();

                                if (n < 0) {
                                        System.out.println(
                                                        n + " is not a positive integer. Please enter a apositive integer (0 to terminate): ");
                                } else if (n > 0) {
                                        walk(n);
                                        System.out.println("\nEnter the size of grid: ");
                                } else {
                                        break;
                                }
                        } catch (InputMismatchException e) {
                                System.out.println("Input is not an integer. Please enter a positive (0 to terminate):");
                                reader.nextLine();
                        }
                } while (true);

                reader.close();
        }
        
Answer Second :
        For use color you can use different color for StdDraw.point()
        
        example : 
        
        StdDraw.setPenColor(StdDraw.BLUE);
        StdDraw.point(n+1, n-1);
        StdDraw.setPenColor(StdDraw.MAGENTA);