Game Play $($handleClickAt$,$ initializeGame, getCurrentBoardAsString, getCurrentTurn$)$:

$*$ handleClickAt:

$*$ Maintain a $2$D grid to represent the game board $($e$.$g$.,$ board$[$ROWS$][$COLS$]).$

$*$ Check if the clicked square is empty.

$*$ Update the board $($board$[$row$][$col$]=$ currentTurn$).$

$*$ Alternate currentTurn between "RING" and "CROSS".

$*$ Return the appropriate TurnResult enum value $($GAME$\_$NOT$\_$OVER, RING$\_$WON, CROSS$\_$WON, or DRAW$).$

$*$ initializeGame:

$*$ Initialize the board grid with empty values $($e$.$g$.,"").$

$*$ Set currentTurn to "RING" $($or randomly based on your preference$).$

$*$ getCurrentBoardAsString:

$*$ Iterate through the board grid and construct a string representation using symbols for empty, ring, and cross $($e$.$g$.,"-","$O$","$X$").$

$*$ getCurrentTurn:

$*$ Return the current turn's value $("$RING$"$ or "CROSS"$).$

$2.$ Win Detection $($handleClickAt$)$:

$*$ handleClickAt:

$*$ After updating the board and turn, check for wins in all directions $($horizontal$,$ vertical, diagonal$)$ from the last placed stone.

$*$ Use helper functions to check for lines of $5$ of the same symbol.

$*$ Update TurnResult to RING$\_$WON or CROSS$\_$WON if a win is found.

$*$ Helper functions:

$*$ Define functions to check for lines of $5$ in a given direction $($e$.$g$.,$ checkLineHorizontal, checkLineVertical, checkLineDiagonal$).$

$*$ These functions should iterate through the board, considering edge cases and preventing out$-$of$-$bounds access.

$3.$ Computer Player $($handleClickAt$,$ initComputerPlayer$)$:

$*$ initComputerPlayer:

$*$ Store the opponent's symbol $("$RING$"$ or "CROSS"$).$

$*$ Set a flag to enable$/$disable the computer player based on the argument $("$NONE$",$ "COMPUTER"$).$

$*$ handleClickAt:

$*$ If the computer player is enabled and it's their turn:

$*$ Choose a legal move $($empty square$).$

$*$ This can be a simple strategy like:

$*$ Prioritize creating or blocking lines of $4.$

$*$ Choose corners or sides if no immediate threats or opportunities exist.

$*$ Randomly choose among remaining legal moves.

$*$ You can explore more advanced strategies using minimax, alpha$-$beta pruning, or machine learning techniques.

public class Gomoku implements GomokuInterface $\{$

private static final int DEFAULT$\_$NUM$\_$ROWS $=15$;

private static final int DEFAULT$\_$NUM$\_$COLS $=15$;

private static final int SQUARES$\_$IN$\_$LINE$\_$FOR$\_$WIN $=5$;

private Square$[][]$ board;

private Square currentTurn;

private boolean enableComputerPlayer;

private Square opponentSymbol;

private Gomoku game;

public Gomoku$($String opponent$)\{$

initComputerPlayer$($opponent$)$;

$\}$

public int getNumRows$()\{$

return DEFAULT$\_$NUM$\_$ROWS;

$\}$

public int getNumCols$()\{$

return DEFAULT$\_$NUM$\_$COLS;

$\}$

public int getNumInLineForWin$()\{$

return SQUARES$\_$IN$\_$LINE$\_$FOR$\_$WIN;

$\}$

public enum TurnResult$\{$

GAME$\_$NOT$\_$OVER,

RING$\_$WON,

CROSS$\_$WON,

DRAW

$\}$

@Override

public TurnResult handleClickAt$($int row, int col$)\{$

if $($board$[$row$][$col$]==$ Square.EMPTY$)\{$

return TurnResult.GAME$\_$NOT$\_$OVER;

$\}$

board$[$row$][$col$]=$ currentTurn;

if $($checkWin$($currentTurn$))\{$

return currentTurn $==$ Square.RING $?$ TurnResult.RING$\_$WON : TurnResult.CROSS$\_$WON;

$\}$

if $($checkDraw$())\{$

return TurnResult.DRAW;

$\}$

currentTurn $=($currentTurn $==$ Square.RING$)?$ Square.CROSS : Square.RING;

return TurnResult.GAME$\_$NOT$\_$OVER;

$\}$

private boolean diagonalRight$($int r$,$ int c$)\{$

Square square$1=$ board$[$r$][$c$]$;

int n $=0$;

for $($int x $=$ c$,$ y $=$ r; x $<$ getNumRows$()$ && y $<$ getNumCols$()$; x$++,$ y$++)\{$

if $($square$1.$toString$()==$ board$[$y$][$x$].$toString$())\{$

n$++$;

$\}$ else $\{$

break;

$\}$

$\}$

return $($n $>=$ getNumInLineForWin$())$;

$\}$

private boolean diagonalLeft$($int r$,$ int c$)\{$

Square square$1=$ board$[$r$][$c$]$;

int n $=0$;

for $($int x $=$ c$,$ y $=$ r; x $<$ getNumRows$()$ && y $<$ getNumCols$()$; x$--,$ y$++)\{$

if $($square$1.$toString$()==$ board$[$y$][$x$].$toString$())\{$

n$++$;

$\}$ else $\{$

break;

$\}$

$\}$

return $($n $>=$ getNumInLineForWin$())$;

$\}$

private boolean horizontal$($int r$,$ int c$)\{$

Square square$1=$ board$[$r$][$c$]$;

int n$=0$;

for $($int i $=$ c; i $=$ GomokuInterface.SQUARES$\_$IN$\_$LINE$\_$FOR$\_$WIN$)$;

$\}$

private boolean vertical$($int r$,$ int c$)\{$

Square square$1=$ board$[$r$][$c$]$;

int n $=0$;

for $($int i $=$ r; i $<$ getNumRows$()$;i$++)\{$

if$($square$1.$toString$()==$ board$[$i$][$c$].$toString$())\{$

n$++$;

$\}$else$\{$

break;

$\}$

$\}$

return $($n $>=$ getNumInLineForWin$())$;

$\}$