JAVA - Can somebody help me find why error would occur at TestBattleShip.testTakeShot?

public static int testTakeShot() { char[][] board = {{'~'}}; int x = 1; int y = 1;

if (x < 0 || x > board[y].length || y < 0 || y > board.length) { return -1; }

if (board[y][x] == Config.HIT_CHAR) { return 1; }

if (board[y][x] == Config.WATER_CHAR) { return 3; }

if (board[y][x] == Config.MISS_CHAR) { return 2; }

return 0; }

Entire Program:

import java.util.Scanner; import java.util.Random;

public class Battleship {

/** * This method converts a String representing a base (or radix) 26 number into a decimal (or * base 10) number. The String representation of the base 26 number uses the letters of the * Latin alphabet to represent the 26 digits. That is, A represents 0, B represents 1, C * represents 2, ..., Y represents 24, and Z represents 25. * * A couple of examples: BAAA = 1 * 26^3 + 0 * 26^2 + 0 * 26^1 + 0 * 26^0 = 17576 ZERTY = 25 * * 26^4 + 4 * 26^3 + 17 * 26^2 + 19 * 26^1 + 24 * 26^0 = 11506714 * * For this method: - use Math.pow to calculate the powers of 26. - don't assume that the input * is in any particular case; use toUpperCase(). - don't check that the input is only 'A' to * 'Z'. - calculate the value of each digit relative to 'A'. - start from either the first or * last character, and calculate the exponent based on the index of each character. * * @param coord The coordinate value in base 26 as described above. * @return The numeric representation of the coordinate. */ public static int coordAlphaToNum(String coord) { // FIXME

int res = 0;

if (coord.length() == 1) { res = (int) ((coord.toUpperCase().charAt(0) - 'A') * Math.pow(26, 0)); } if (coord.length() == 2) { res = (int) ((coord.toUpperCase().charAt(0) - 'A') * Math.pow(26, 1)) + (int) ((coord.toUpperCase().charAt(1) - 'A') * Math.pow(26, 0)); }

if (coord.length() == 3) { res = (int) ((coord.toUpperCase().charAt(0) - 'A') * Math.pow(26, 2)) + (int) ((coord.toUpperCase().charAt(1) - 'A') * Math.pow(26, 1)) + (int) ((coord.toUpperCase().charAt(2) - 'A') * Math.pow(26, 0)); }

if (coord.length() == 4) { res = (int) ((coord.toUpperCase().charAt(0) - 'A') * Math.pow(26, 3)) + (int) ((coord.toUpperCase().charAt(1) - 'A') * Math.pow(26, 2)) + (int) ((coord.toUpperCase().charAt(2) - 'A') * Math.pow(26, 1)) + (int) ((coord.toUpperCase().charAt(3) - 'A') * Math.pow(26, 0)); }

if (coord.length() == 5) { res = (int) ((coord.toUpperCase().charAt(0) - 'A') * Math.pow(26, 4)) + (int) ((coord.toUpperCase().charAt(1) - 'A') * Math.pow(26, 3)) + (int) ((coord.toUpperCase().charAt(2) - 'A') * Math.pow(26, 2)) + (int) ((coord.toUpperCase().charAt(3) - 'A') * Math.pow(26, 1)) + (int) ((coord.toUpperCase().charAt(4) - 'A') * Math.pow(26, 0)); }

return res; }

/** * This method converts an int value into a base (or radix) 26 number, where the digits are * represented by the 26 letters of the Latin alphabet. That is, A represents 0, B represents 1, * C represents 2, ..., Y represents 24, and Z represents 25. A couple of examples: 17576 is * BAAA, 11506714 is ZERTY. * * The algorithm to convert an int to a String representing these base 26 numbers is as follows: * - Initialize res to the input integer - The next digit is determined by calculating the * remainder of res with respect to 26 - Convert this next digit to a letter based on 'A' - Set * res to the integer division of res and 26 - Repeat until res is 0 * * @param coord The integer value to covert into an alpha coordinate. * @return The alpha coordinate in base 26 as described above. If coord is negative, an empty * string is returned. */ public static String coordNumToAlpha(int coord) {

String str = "";

if (coord == 0) { str = "A"; }

while (coord > 0) { int res = coord % 26; coord = coord / 26; str = str + (char) ('A' + res); }

String reverse = ""; for (int i = str.length() - 1; i >= 0; i--) { reverse = reverse + str.charAt(i); }

return reverse;

}

/** * Prompts the user for an integer value, displaying the following: "Enter the valName (min to * max): " Note: There should not be a new line terminating the prompt. valName should contain * the contents of the String referenced by the parameter valName. min and max should be the * values passed in the respective parameters. * * After prompting the user, the method will read an int from the console and consume an entire * line of input. If the value read is between min and max (inclusive), that value is returned. * Otherwise, "Invalid value." terminated by a new line is output and the user is prompted * again. * * @param sc The Scanner instance to read from System.in. * @param valName The name of the value for which the user is prompted. * @param min The minimum acceptable int value (inclusive). * @param min The maximum acceptable int value (inclusive). * @return Returns the value read from the user. */ public static int promptInt(Scanner sc, String valName, int min, int max) {

int line; boolean ValidValue = false;

do { System.out.print("Enter the " + valName + " (" + min + " to " + max + "): "); line = sc.nextInt(); sc.nextLine(); if ((line >= min) && (line <= max)) { ValidValue = true; } else { System.out.println("Invalid value."); } } while (!ValidValue);

return line; }

/** * Prompts the user for an String value, displaying the following: "Enter the valName (min to * max): " Note: There should not be a new line terminating the prompt. valName should contain * the contents of the String referenced by the parameter valName. min and max should be the * values passed in the respective parameters. * * After prompting the user, the method will read an entire line of input, trimming any trailing * or leading whitespace. If the value read is (lexicographically ignoring case) between min and * max (inclusive), that value is returned. Otherwise, "Invalid value." terminated by a new line * is output and the user is prompted again. * * @param sc The Scanner instance to read from System.in. * @param valName The name of the value for which the user is prompted. * @param min The minimum acceptable String value (inclusive). * @param min The maximum acceptable String value (inclusive). * @return Returns the value read from the user. */ public static String promptStr(Scanner sc, String valName, String min, String max) {

System.out.print("Enter the " + valName + " (" + min + " to " + max + "): "); String line = sc.nextLine(); line = line.trim();

String min1 = min.toUpperCase(); String max1 = max.toUpperCase(); String line1 = line.toUpperCase();

if (min1.compareTo(line1) <= 0 && line1.compareTo(max1) <= 0) { return line1; } else { System.out.println("Invalid value."); return promptStr(sc, valName, min, max); }

}

/** * Prompts the user for an char value. The prompt displayed is the contents of the String * referenced by the prompt parameter. Note: There should not be a new line terminating the * prompt. * * After prompting the user, the method will read an entire line of input and return the first * non-whitespace character in lower case. * * @param sc The Scanner instance to read from System.in * @param prompt The user prompt. * @return Returns the first non-whitespace character (in lower case) read from the user. If * there are no non-whitespace characters read, the null character is returned. */ public static char promptChar(Scanner sc, String prompt) {

System.out.print(prompt);

String line = sc.nextLine(); line = line.trim(); String line1 = line.toLowerCase();

return line1.charAt(0); }

/** * Initializes a game board so that all the entries are Config.WATER_CHAR. * * @param board The game board to initialize. */ public static void initBoard(char board[][]) {

for (int i = 0; i < board.length; i++) { for (int j = 0; j < board[i].length; j++) { board[i][j] = Config.WATER_CHAR; } } }

/** * Prints the game boards as viewed by the user. This method is used to print the game boards as * the user is placing their ships and during the game play. * * Some notes on the display: - Each column printed will have a width of Config.MAX_COL_WIDTH. - * Each row is followed by an empty line. - The values in the headers and cells are to be right * justified. * * @param board The board to print. * @param caption The board caption. */ public static void printBoard(char board[][], String caption) {

System.out.println(caption + ":"); System.out.print(" ");

for (int i = 0; i < (board[0].length - 1); ++i) { System.out.print((char) ('A' + i) + " "); } System.out.println((char) ('A' + (board[0].length - 1)));

for (int i = 0; i < board.length; ++i) { System.out.print(" " + i + " "); for (int j = 0; j < (board[0].length - 1); j++) { System.out.print(board[i][j] + " "); } System.out.println(board[i][board[0].length - 1]); System.out.println(); }

}

/** * Determines if a sequence of cells of length len in a game board is clear or not. This is used * to determine if a ship will fit on a given game board. The x and y coordinates passed in as * parameters represent the top-left cell of the ship when considering the grid. * * @param board The game board to search. * @param xcoord The x-coordinate of the top-left cell of the ship. * @param ycoord The y-coordinate of the top-left cell of the ship. * @param len The length of the ship. * @param dir true if the ship will be vertical, otherwise horizontal * @return 1 if the cells to be occupied by the ship are all Config.WATER_CHAR, -1 if the cells * to be occupied are not Config.WATER_CHAR, and -2 if the ship would go out-of-bounds * of the board. */ public static int checkWater(char board[][], int xcoord, int ycoord, int len, boolean dir) {

int checkPoint = 0;

if (dir) { for (int i = 0; i < len; ++i) { if ((len + ycoord) > board.length) { checkPoint = -2; break; }

if (ycoord < 0 || ycoord >= board.length) { checkPoint = -2; break; }

if (xcoord < 0 || xcoord >= board[0].length) { checkPoint = -2; break; } if (board[i + ycoord][xcoord] != Config.WATER_CHAR) { checkPoint = -1; break; } else { checkPoint = 1; } }

} else if (!dir) { for (int i = 0; i < len; ++i) { if ((len + xcoord) > board[0].length) { checkPoint = -2; break; } if (ycoord < 0 || ycoord >= board.length) { checkPoint = -2; break; }

if (xcoord < 0 || xcoord >= board[0].length) { checkPoint = -2; break; } if (board[ycoord][xcoord + i] != Config.WATER_CHAR) { checkPoint = -1; break; } else { checkPoint = 1; } } } return checkPoint;

}

/** * Checks the cells of the game board to determine if all the ships have been sunk. * * @param board The game board to check. * @return true if all the ships have been sunk, false otherwise. */ public static boolean checkLost(char board[][]) {

boolean checkPoint = true;

for (int i = 0; i < board.length; i++) { for (int j = 0; j < board[i].length; j++) { if (board[i][j] != Config.WATER_CHAR && board[i][j] != Config.HIT_CHAR && board[i][j] != Config.MISS_CHAR) { checkPoint = false; } } } return checkPoint; }

/** * Places a ship into a game board. The coordinate passed in the parameters xcoord and ycoord * represent the top-left coordinate of the ship. The ship is represented on the game board by * the Character representation of the ship id. (For this method, you can assume that the id * parameter will only be values 1 through 9.) * * @param board The game board to search. * @param xcoord The x-coordinate of the top-left cell of the ship. * @param ycoord The y-coordinate of the top-left cell of the ship. * @param len The length of the ship. * @param dir true if the ship will be vertical, otherwise horizontal. * @param id The ship id, assumed to be 1 to 9. * @return false if the ship goes out-of-bounds of the board, true otherwise. */ public static boolean placeShip(char board[][], int xcoord, int ycoord, int len, boolean dir, int id) { boolean checkPoint = false;

if (dir) { for (int i = 0; i < len; ++i) { if ((len + ycoord) > board.length) { checkPoint = false; break; } if (board[i + ycoord][xcoord] == Config.WATER_CHAR) { board[i + ycoord][xcoord] = (char) (id + '0'); checkPoint = true; }

}

} else if (!dir) { for (int i = 0; i < len; ++i) { if ((len + xcoord) > board[i].length) { checkPoint = false; break; } if (board[ycoord][xcoord + i] == Config.WATER_CHAR) { board[ycoord][xcoord + i] = (char) (id + '0'); checkPoint = true; }

} } return checkPoint;

}

/** * Randomly attempts to place a ship into a game board. The random process is as follows: 1 - * Pick a random boolean, using rand. True represents vertical, false horizontal. 2 - Pick a * random integer, using rand, for the x-coordinate of the top-left cell of the ship. The number * of integers to choose from should be calculated based on the width of the board and length of * the ship such that the placement of the ship won't be out-of-bounds. 3 - Pick a random * integer, using rand, for the y-coordinate of the top-left cell of the ship. The number of * integers to choose from should be calculated based on the height of the board and length of * the ship such that the placement of the ship won't be out-of-bounds. 4 - Verify that this * random location can fit the ship without intersecting another ship (checkWater method). If * so, place the ship with the placeShip method. * * It is possible for the configuration of a board to be such that a ship of a given length may * not fit. So, the random process will be attempted at most Config.RAND_SHIP_TRIES times. * * @param board The game board to search. * @param len The length of the ship. * @param id The ship id, assumed to be 1 to 9.. * @param rand The Random object. * @return true if the ship is placed successfully, false otherwise. */ public static boolean placeRandomShip(char board[][], int len, int id, Random rand) {

boolean rightPlace = false;

for (int i = 0; i < Config.RAND_SHIP_TRIES; i++) { boolean dir = rand.nextBoolean(); int xcoord = 0; int ycoord = 0;

if (dir) { xcoord = rand.nextInt(board[0].length); ycoord = rand.nextInt(board.length - len + 1);

} else { xcoord = rand.nextInt(board[0].length - len + 1); ycoord = rand.nextInt(board.length); }

if (checkWater(board, xcoord, ycoord, len, dir) == 1) { rightPlace = placeShip(board, xcoord, ycoord, len, dir, id); if (rightPlace) { return true; } } } return false;

}

/** * This method interacts with the user to place a ship on the game board of the human player and * the computer opponent. The process is as follows: 1 - Print the user primary board, using the * printBoard. 2 - Using the promptChar method, prompt the user with "Vertical or horizontal? * (v/h) ". A response of v is interpreted as vertical. Anything else is assumed to be * horizontal. 3 - Using the promptInt method, prompt the user for an integer representing the * "ship length", where the minimum ship length is Config.MIN_SHIP_LEN and the maximum ship * length is width or height of the game board, depending on the input of the user from step 1. * 4 - Using the promptStr method, prompt the user for the "x-coord". The maximum value should * be calculated based on the width of the board and the length of the ship. You will need to * use the coordAlphaToNum and coordNumToAlpha methods to covert between int and String values * of coordinates. 5 - Using the promptInt method, prompt the user for the "y-coord". The * maximum value should be calculated based on the width of the board and the length of the * ship. 6 - Check if there is space on the board to place the ship. 6a - If so: - Place the * ship on the board using placeShip. - Then, call placeRandomShip to place the opponents ships * of the same length. - If placeRandomShip fails, print out the error message (terminated by a * new line): "Unable to place opponent ship: id", where id is the ship id, and return false. 6b * - If not: - Using promptChar, prompt the user with "No room for ship. Try again? (y/n): " - * If the user enters a 'y', restart the process at Step 1. - Otherwise, return false. * * @param sc The Scanner instance to read from System.in. * @param boardPrime The human player board. * @param boardOpp The opponent board. * @param id The ship id, assumed to be 1 to 9. * @param rand The Random object. * @return true if ship placed successfully by player and computer opponent, false otherwise. */ public static boolean addShip(Scanner sc, char boardPrime[][], char boardOpp[][], int id, Random rand) { char userInput = 'n';

do { printBoard(boardPrime, "My Ships"); if (promptChar(sc, "Vertical or horizontal? (v/h): ") == 'v') { int shipLength = promptInt(sc, "ship length", Config.MIN_SHIP_LEN, boardPrime.length); String xCoord = promptStr(sc, "x-coord", "A", coordNumToAlpha(boardPrime[0].length - 1));

int xcoord = coordAlphaToNum(xCoord); int yCoord = promptInt(sc, "y-coord", 0, (boardPrime.length - shipLength));

if (checkWater(boardPrime, xcoord, yCoord, shipLength, true) == 1) { placeShip(boardPrime, xcoord, yCoord, shipLength, true, id);

boolean oppShip = placeRandomShip(boardOpp, shipLength, id, rand); if (!oppShip) { System.out.print("Unable to place opponent ship: " + id); return false; } } else { userInput = promptChar(sc, "No room for ship. Try again? (y/n): "); } }

else { int shipLen = promptInt(sc, "ship length", Config.MIN_SHIP_LEN, boardPrime[0].length); String xCoord = promptStr(sc, "x-coord", "A", coordNumToAlpha(boardPrime[0].length - shipLen)); int xcoord = coordAlphaToNum(xCoord); int yCoord = promptInt(sc, "y-coord", 0, (boardPrime.length - 1));

if (checkWater(boardPrime, xcoord, yCoord, shipLen, false) == 1) { placeShip(boardPrime, xcoord, yCoord, shipLen, false, id);

boolean oppBoard = placeRandomShip(boardOpp, shipLen, id, rand); if (!oppBoard) { System.out.print("Unable to place opponent ship: " + id); return false; } } else { userInput = promptChar(sc, "No room for ship. Try again? (y/n): "); } } } while (userInput == 'y');

return true;

}

/** * Checks the state of a targeted cell on the game board. This method does not change the * contents of the game board. * * @return 3 if the cell was previously targeted. 2 if the shot would be a miss. 1 if the shot * would be a hit. -1 if the shot is out-of-bounds. */ public static int takeShot(char[][] board, int x, int y) { if(board == null || x < 0 || board.length >= x || y < 0 || y >= board[x].length) { return -1; } char value = board[x][y]; if(value == Config.HIT_CHAR) { return 3; } else if(value == Config.WATER_CHAR) { return 2; } else { return 1; } }

/** * Interacts with the user to take a shot. The procedure is as follows: 1 - Using the promptStr * method, prompt the user for the "x-coord shot". The maximum value should be based on the * width of the board. You will need to use the coordAlphaToNum and coordNumToAlpha methods to * covert between int and String values of coordinates. 2 - Using the promptInt method, prompt * the user for the "y-coord shot". The maximum value should be calculated based on the width of * the board. 3 - Check the shot, using the takeShot method. If it returns: -1: Print out an * error message "Coordinates out-of-bounds!", terminated by a new line. 3: Print out an error * message "Shot location previously targeted!", terminated by a new line. 1 or 2: Update the * cells in board and boardTrack with Config.HIT_CHAR or Config.MISS_CHAR accordingly. This * process should repeat until the takeShot method returns 1 or 2. * * @param sc The Scanner instance to read from System.in. * @param board The computer opponent board (containing the ship placements). * @param boardTrack The human player tracking board. */ public static void shootPlayer(Scanner sc, char[][] board, char[][] boardTrack) {

String xCoord = promptStr(sc, "x-coord shot", "A", coordNumToAlpha(board[0].length - 1)); int xcoord = coordAlphaToNum(xCoord); int ycoord = promptInt(sc, "y-coord shot", 0, (board.length - 1)); do { if (takeShot(board, xcoord, ycoord) == -1) { System.out.println( "Coordinates out-of-bounds!"); } if (takeShot(board, xcoord, ycoord) == 3) { System.out.println("Shot location previously targeted!"); } if(takeShot(board, xcoord, ycoord) == 1) { boardTrack[ycoord][xcoord] = Config.HIT_CHAR; } if (takeShot(board, xcoord, ycoord) == 2) { boardTrack[ycoord][xcoord] = Config.MISS_CHAR; } } while(takeShot(board, xcoord, ycoord) == 1 || takeShot(board, xcoord, ycoord) == 2); }

/** * Takes a random shot on the game board. The random process works as follows: 1 - Pick a random * valid x-coordinate 2 - Pick a random valid y-coordinate 3 - Check the shot, using the * takeShot method. This process should repeat until the takeShot method returns 1 or 2, then * update the cells in board with Config.HIT_CHAR or Config.MISS_CHAR accordingly. * * Note: Unlike the placeRandomShip method, this method continues until it is successful. This * may seem risky, but in this case the random process will terminate (find an untargeted cell) * fairly quickly. For more details, see the appendix of the Big Program 1 subject. * * @param rand The Random object. * @param board The human player game board. */ public static void shootComputer(Random rand, char[][] board) {

int xcoord = rand.nextInt(board[0].length); int ycoord = rand.nextInt(board.length); do { if (takeShot(board, xcoord, ycoord) == 1) { board[ycoord][xcoord] = Config.HIT_CHAR; } if (takeShot(board, xcoord, ycoord) == 2) { board[ycoord][xcoord] = Config.MISS_CHAR; } } while(takeShot(board, xcoord, ycoord) != 1 || takeShot(board, xcoord, ycoord) != 2); }

/** * This is the main method for the Battleship game. It consists of the main game and play again * loops with calls to the various supporting methods. When the program launches (prior to the * play again loop), a message of "Welcome to Battleship!", terminated by a newline, is * displayed. After the play again loop terminiates, a message of "Thanks for playing!", * terminated by a newline, is displayed. * * The Scanner object to read from System.in and the Random object with a seed of Config.SEED * will be created in the main method and used as arguments for the supporting methods as * required. * * Also, the main method will require 3 game boards to track the play: - One for tracking the * ship placement of the user and the shots of the computer, called the primary board with a * caption of "My Ship". - One for displaying the shots (hits and misses) taken by the user, * called the tracking board with a caption of "My Shots"; and one for tracking the ship * placement of the computer and the shots of the user. - The last board is never displayed, but * is the primary board for the computer and is used to determine when a hit or a miss occurs * and when all the ships of the computer have been sunk. Notes: - The size of the game boards * are determined by the user input. - The game boards are 2d arrays that are to be viewed as * row-major order. This means that the first dimension represents the y-coordinate of the game * board (the rows) and the second dimension represents the x-coordinate (the columns). * * @param args Unused. */ public static void main(String[] args) {

System.out.println("Welcome to Battleship!"); Scanner sc = new Scanner(System.in); Random rand = new Random(Config.SEED);

int boardHeight = 0; int boardWidth = 0; char[][] myShip; char[][] myShot; char[][] lastBoard; char userInput;

do { boardHeight = promptInt(sc, "board height", Config.MIN_HEIGHT, Config.MAX_HEIGHT); boardWidth = promptInt(sc, "board width", Config.MIN_WIDTH, Config.MAX_WIDTH); System.out.println();

myShip = new char[boardHeight][boardWidth]; myShot = new char[boardHeight][boardWidth]; lastBoard = new char[boardHeight][boardWidth];

initBoard(myShip); initBoard(myShot); initBoard(lastBoard);

int id = promptInt(sc, "number of ships", Config.MIN_SHIPS, Config.MAX_SHIPS);

for (int i = 1; i <= id; ++i) { boolean addSuccess = addShip(sc, myShip, myShot, i, rand); if (!addSuccess) { userInput = promptChar(sc, "Error adding ships. Restart game? (y/n): "); break; } } printBoard(myShip, "My Ships"); myShot = new char[boardHeight][boardWidth]; initBoard(myShot); printBoard(myShot, "My Shots"); shootPlayer(sc, myShip, myShot);

userInput = promptChar(sc, "Would you like to play again? (y/n): "); } while (userInput == 'y');

System.out.println("Thanks for playing!"); }

}