This assignment is based on Programming Project P13.7 in Big Java: Late Objects

You are currently located inside a maze. The walls of the maze are indicated by asterisks (*).

Use the following recursive approach to check whether you can escape from the maze:

If you are at an exit, return true.

Recursively check whether you can escape from one of the empty neighboring locations without visiting the current location.

This method merely tests whether there is a path out of the maze.

Extra credit (+20 points) if you can print out a path that leads to an exit.

Resources

Maze file (as shown above): maze1_9x9.txt

this is the file

* ******* * * * * ***** * * * * * * * *** * * * * *** * * * * * * ******* * 

Maze object class UML diagram: Maze_UML.png

Maze test client code: MazeTester.java

import java.io.*; import java.util.Scanner; /* * MazeTester.java * * Requires: Maze.java */ public class MazeTester { private static char[][] maze; private static int width, height; private static final Scanner KBD = new Scanner(System.in); private static final PrintStream OUT = System.out; /* * program for testing the Maze class: * 1. get maze file name, width and height from user * 2. make the maze 2-D char array * 3. read the maze from the file * 4. create a Maze object with the maze * 5. get the start point from the user * 6. solve the maze (if possible), tell user what happened */ public static void main(String[] args) { final int ERROR=1; String fName = null; int r=0, c=0; // maze coordinates for entrance try { // get maze file name from user // abort the program if any input is not valid OUT.print("File name? "); fName = getString("\tInvalid file name, bye!"); } catch (IOException e) { OUT.println(e.getMessage()); System.exit(ERROR); } try (Scanner fileReader = new Scanner(new File(fName))) { // get maze file name, width and height from user OUT.print("Maze width? "); width = getDimension("\tInvalid width, bye!"); OUT.print("Maze height? "); height = getDimension("\tInvalid height, bye!"); // make the maze 2-D char array maze = new char[height][width]; // read the maze from the file readMaze(fileReader); // showMaze(); // create a Maze object with the maze Maze solver = new Maze(maze); // get the start point from the user // abort the program if any input is not valid OUT.print("OK, maze is loaded ... where is the entrance (row# col#)? "); r = getCoordinate(width, "\tInvalid row coordinate, bye!"); c = getCoordinate(height, "\tInvalid column coordinate, bye!"); // solve the maze (if possible), tell user what happened if (solver.escape(r-1, c-1)) { OUT.println("Yay, I made it through the maze!!!"); } else { OUT.println("Help, there's no way out!!!"); } // end if ... else } catch (IOException e) { OUT.println(e.getMessage()); System.exit(1); } // end try...catch } // end main /* * gets a String from the user and validates it * as a non-null, non-empty String before returning it * throws an IOException with the given error String * if invalid input */ private static String getString(String error) throws IOException { String result = KBD.nextLine(); if (result == null || result.length() == 0) { throw new IOException(error); } return result; } // end getString /* * gets a dimension from the user and validates it * as a positive integer before returning it * throws an IOException with the given error String * if invalid input */ private static int getDimension(String error) throws IOException { int result = 0; if (KBD.hasNextInt()) { result = KBD.nextInt(); if (result  dimension) { throw new IOException(error); } } else { throw new IOException(error); } return result; } // getCoordinate /* * loads the maze using the given Scanner to the input file */ private static void readMaze(Scanner reader) throws IOException { int rowIndex = 0; while (reader.hasNextLine() && rowIndex  
 
 
Sample Run (user input in color)
 
File name? maze1_9x9.txt Maze width? 9 Maze height? 9 OK, maze is loaded ... where is the entrance (row# col#)? 5 4 Yay, I made it through the maze!!!
 
 
 
 
 
References
 
Big Java: Late Objects:
 
Two-Dimensional Arrays: Chapter 6, Section 6.7
 
Reading and Writing Text Files: Chapter 7, Section 7.1
 
Text Input and Output: Chapter 7, Section 7.2
 
Exception Handling: Chapter 7, Section 7.4