Assignment Overview

This assignment guides you in building a set of classes to support a program that finds paths through a cave.
By the end of Unit 4, you will have a program that can:

Read a 2D cave layout from a file,
Search the layout to find a path to a mirror pool,
Print the path to take.

In this unit, you will:

Build the infrastructure for the project,
Store cave data in a two-dimensional structure,
Search the structure for a simple path from start to finish,
Read cave data from a text file.

Preparation

See the course announcements for a link to the GitHub repository for this assignment.

Directions

Write a class CaveExplorer that includes the following methods and features:

Required Methods & Functionality

Constructor (no parameters):
- Creates the 2D structure shown below (hardcoded).
- Cave layout uses:
  'R' = rock, '.' = clear path, 'M' = mirror pool, 'S' = self (start).
- Example layout (hardcoded):
```
R R R R R R
R . . S R R
R . R R R R
R . M R R R
R R R R R R
```
- For the initial configuration, toString() would output:
  "RRRRRR\nR..SRR\nR.RRRR\nR.MRRR\nRRRRRR\n"
toString() method:
- Returns a string (including new lines) showing the current state of the cave.
solve() method:
- Returns true if there is a path from 'S' (self/start) to 'M' (mirror pool), false otherwise.
- Must search in four directions (N/E/S/W) and avoid infinite loops.
getPath() method:
- Returns a string showing the path directions to reach the mirror pool.
- For the example, it would return "wwsse" (West, West, South, South, East).
- Returns an empty string if there is no path.
Constructor (with one String parameter):
- Receives the name of a text file containing the cave layout.
- The file begins with two integers (number of rows and columns), followed by the layout itself.
- Example file contents:
```
5 6
RRRRRR
R..SRR
R.RRRR
R.MRRR
RRRRRR
```
- The cave layout should have a path requiring at least 4 moves in at least two directions.
- There must be exactly one path through the cave (from any location, only one unvisited move is possible at each step).
main method:
- Test your class by creating at least two CaveExplorer objects.
- For each object:
  - Solve for the path,
  - Print the starting layout,
  - Print the final layout,
  - Print the path taken (if it exists).
- Follow this order for your outputs.

Additional Notes

If you need help reading from a file, refer to the section on Scanners:
Java Notes on Using Scanners
You may use your favorite editor to modify the text file with the cave data.

Solution

import java.io.*;import java.util.*;public class CaveExplorer {

// data fieldschar [][] structure ;static ArrayList<Character> ThePath ;static ArrayList<String> readFromFile ;

//Constructor with no parameterspublic CaveExplorer() {

structure = new char[][] { { 'R', 'R', 'R', 'R', 'R', 'R' },

{ 'R', '.', '.', 'S', 'R' , 'R'},

{ 'R', '.', 'R', 'R', 'R' , 'R'},

{ 'R', '.', 'M', 'R', 'R' , 'R'},

{ 'R', 'R', 'R', 'R', 'R', 'R' }, };

ThePath = new ArrayList();readFromFile = new ArrayList(); }

//toString - no parameters, returns a stringpublic String toString(){

String result ="";

for(int i = 0 ; i < structure.length ; i++){

for(int j = 0 ; j < structure[0].length ; j++){

result += structure[i][j]; } result +="\n"; }

return result; }

//solve - no parameters, returns a boolean true if there is a path to the mirror pool, and false if there is notpublic boolean solve(){

boolean travel[][] = new boolean[structure.length][structure[0].length];

boolean checked = false;

for (int i = 0; i < structure.length; i++) {

for (int j = 0; j < structure[0].length; j++) {

if (structure[i][j] == 'S'&& !travel[i][j])

if (checkpath(structure, i, j, travel)) { checked = true; break; }}}

if (checked) return true;else return false;

}

// checkpath to pass through 2d array character to find the pathpublic boolean checkpath(char structure[][],int i, int j,boolean travel[][]){

if ((i >= 0 && i < structure.length&& j >= 0&& j < structure[0].length)&& structure[i][j] != 'R'&& !travel[i][j]) { travel[i][j] = true;if (structure[i][j] == 'M') return true;if (checkpath(structure, i - 1,j, travel)) {ThePath.add('N'); return true;}if (checkpath(structure, i, j - 1, travel)) {ThePath.add('W'); return true;}if (checkpath(structure, i + 1, j, travel)) {ThePath.add('S'); return true;}if (checkpath(structure, i, j + 1,travel)) {ThePath.add('E'); return true;}}return false;

}

//getPath - no parameters, returns a String showing the path taken to get to the mirror poolpublic String getPath() {if(ThePath.size() == 0) solve();

String result ="";

Collections.reverse(ThePath);

for(Character getpath :ThePath) result += getpath;

return result;

}

// Constructor with one String parameterpublic CaveExplorer (String fname) throws Exception {

Scanner input =null;ThePath = new ArrayList();readFromFile = new ArrayList();ThePath.clear();int row , col;

try{ input = new Scanner(new File(fname));} catch (FileNotFoundException e ) {

System.out.println("File not found " );

} catch (Exception e ) {

System.out.println(e );

}row = input.nextInt();col = input.nextInt();input.nextLine();

structure = new char[row][col];String value ="";

while (input.hasNextLine()) { value = input.nextLine() ; readFromFile.add(value); }int index = 0 ;for(String data:readFromFile) { if(data.length()==col) { structure[index++] = data.toCharArray(); } else { throw new Exception("Error "); } } }

public static void main(String[] args) {

// first objectCaveExplorer cave = new CaveExplorer();

System.out.println(cave.toString());System.out.println("There is a path : "+cave.solve());System.out.println("getPath: "+cave.getPath());

// second object

try {

CaveExplorer cave2 = new CaveExplorer("testcave.txt");

System.out.println("\n\n"+cave2.toString());System.out.println("There is a path : "+cave2.solve());System.out.println("getPath: "+cave2.getPath());

}catch (Exception e) { System.out.println(e ); }

}

testcave.txt

5 6RRRRRRR..SRRR.RRRRR.MRRRRRRRRR

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Java Assignment: CaveExplorer Path-Finding Project