This is a simple Minimax Algorithm based Tic Tac Toe in Java Console. I developed this as a hobby project and there is also some bugs.So,this is not a 100% completed project,but you can learn easily from the code.There are many tic tac toe codes available and this is a different approach.
Introduction
There are 3 java files:
- tikitaka.java
- bordmaker.java
- AIPlayer.java
tikitaka is the main java file and this contains checking of status of gameplay ie Winning /Losing/Draw.
bordmaker is used for making User Interface for board in console.
AIPlayer is the java class which performs Minimax Algorithm[wikipedia]. Minimax is a recursive. You can also use Alpha Beta Prunning Method[], which is used mostly.Minimax is a beginner level.
Let’s Start…
1) Create a New Project,Name it as tikitaka (I am using NetBeans for Java projects)
2) Create class tikitaka.java, You can just read the code and it is easy to understand.This function ai.minimax(temp,player ) is the minimax function which gives the next calculated movement.
package tikitaka;
import java.util.Random;
import java.util.Scanner;
public class tikitata {
public static int player;
static int flag =0; //temp var for wining the game true
public static String[][] s = new String[11][11];
//bordmaker q = new bordmaker();
void check_A(){
bordmaker q = new bordmaker();
if(s[0][0]==s[1][0]){
if(s[1][0]==s[2][0]){
if(s[1][0]=="X"){
System.out.print("Player A win the Game :)\n");
q.dispbrd();
System.exit(0);
}
}
}
if(s[0][0]==s[0][1]){
if(s[0][0]==s[0][2]){
if(s[0][0]=="X"){
System.out.print("Player A win the Game :)\n");
q.dispbrd();
System.exit(0);
}
}
}
if(s[1][0]==s[1][1]){
if(s[1][0]==s[1][2]){
if(s[1][0]=="X"){
System.out.print("Player A win the Game :)\n");
q.dispbrd();
System.exit(0);
}
}
}
if(s[2][0]==s[2][1]){
if(s[2][0]==s[2][2]){
if(s[2][0]=="X"){
System.out.print("Player A win the Game :)\n");
q.dispbrd();
System.exit(0);
}
}
}
if(s[0][1]==s[1][1]){
if(s[1][1]==s[2][1]){
if(s[0][1]=="X"){
System.out.print("Player A win the Game :)\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][2]==s[1][2]){
if(s[1][2]==s[2][2]){
if(s[0][2]=="X"){
System.out.print("Player A win the Game :)\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][0]==s[1][1]){
if(s[1][1]==s[2][2]){
if(s[1][1]=="X"){
System.out.print("Player A win the Game :)\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][2]==s[1][1]){
if(s[1][1]==s[2][0]){
if(s[1][1]=="X"){
System.out.print("Player A win the Game :)\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][0]==s[1][0]){
if(s[1][0]==s[2][0]){
if(s[1][0]=="X"){
System.out.print("Player A win the Game :)\n");q.dispbrd();
System.exit(0);
}
}
}
}
void check_B(){
int chb = 1;bordmaker q = new bordmaker();
if(s[0][0]==s[0][1]){
if(s[0][0]==s[0][2]){
if(s[0][2]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[1][0]==s[1][1]){
if(s[1][0]==s[1][2]){
if(s[1][0]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[2][0]==s[2][1]){
if(s[2][0]==s[2][2]){
if(s[2][0]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][1]==s[1][1]){
if(s[1][1]==s[2][1]){
if(s[0][1]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][2]==s[1][2]){
if(s[1][2]==s[2][2]){
if(s[0][2]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][0]==s[1][1]){
if(s[1][1]==s[2][2]){
if(s[1][1]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][2]==s[1][1]){
if(s[1][1]==s[2][0]){
if(s[0][2]=="O"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
if(s[0][0]==s[1][0]){
if(s[1][0]==s[2][0]){
if(s[1][0]=="X"){
System.out.print("Computer win the Game :(\n");q.dispbrd();
System.exit(0);
}
}
}
}
public static void main (String[] args) throws InterruptedException{
Scanner e = new Scanner (System.in);
tikitata t =new tikitata();
Random r = new Random();
int low =0; int high =3;
AIPlayer ai = new AIPlayer();
int a;
int row,col; //entered row and column
for(int i=0;i<3;i++){
for(int j=0;j<3;j++){
s[i][j] =" ";
}
}
System.out.print("Welcome to AI Tic-Tac_toe in Console \n");
bordmaker q = new bordmaker();
int temp =16;
for(a=1;a<10;a++){
q.dispbrd();
if(a%2 !=0){
System.out.println("Enter the row and column for player A (X) ");
player = 21;
row= e.nextInt();
col =e.nextInt();
do{
if((row<0&&row>3)&& (col<0&&col>3)){
System.out.println("Wrong Enter,Please enter row and col again");
row= e.nextInt();
col =e.nextInt();
}
if(s[row][col]!=" "){
System.out.println("Wrong Enter,Please enter row and col again");
row= e.nextInt();
col =e.nextInt();
}
}while(s[row][col]!=" ");
System.out.println("\n");
t.s[row][col] = "X";
t.check_A();
}
else{
player = 29;
int [] result = ai.minimax(temp,player );
//temp--;
row = result[1];
col=result[2];
//System.out.println("BestScore"+result[0]);
//System.out.println("Col is "+col);
System.out.println("\n");
t.s[row][col]="O";
t.check_B();
}
}//if for a%2!=0 closed
System.out.println("Draw match");
}
}
2) bordmaker.java
package tikitaka;
/**
*
* Student
*/
public class bordmaker extends tikitata {
public void dispbrd(){
//System.out.println(" | | ");
System.out.println(s[0][0]+" | "+s[0][1]+" | "+s[0][2]);
System.out.println("-----------");
System.out.println(s[1][0]+" | "+s[1][1]+" | "+s[1][2]);
System.out.println("-----------");
System.out.println(s[2][0]+" | "+s[2][1]+" | "+s[2][2]);
//System.out.println(" | | ");
}
}
3) AIPlayer.java
package tikitaka;
import java.util.ArrayList;
import java.util.List;
import com.sun.xml.internal.ws.api.pipe.NextAction;
public class AIPlayer extends tikitata {
//player may be computer(29) or opponent(21)
public int[] minimax(int depth,int player){
List nextMoves = generateMoves();
//System.out.println(player);
int bestScore =(player==29)?Integer.MIN_VALUE:Integer.MAX_VALUE;
//System.out.println(bestScore);
int currentScore;
int bestRow =-1;
int bestCol =-1;
if(nextMoves.isEmpty() || depth ==0 ) {
//System.out.print("nextMoveEmpty()");
bestScore = evaluate();
}
else {
for (int[] moves:nextMoves){
if(player ==21){
s[moves[0]][moves[1]] = "X";
}else if(player ==29){
s[moves[0]][moves[1]] = "O";
}
if(player == 29){
currentScore =minimax(depth-1, 21)[0]; //Dont know about this [0]
if(currentScore >bestScore){
bestScore = currentScore;
bestRow = moves[0];
bestCol = moves[1];
}
}
else {
currentScore =minimax(depth-1, 29)[0]; //Dont know about this [0]
if(currentScore 0){
Score=Score*10;
}
else if(Score <0){
return 0;
}
else {
Score =1;
}
}
else if(s[row3][col3]=="X"){
if(Score < 0){
Score =Score*10;
}
else if(Score >1){
return 0;
}
else {
Score =1;
}
}
return Score;
}
private List generateMoves() {
List nextMoves = new ArrayList();
if(eval_A() || eval_B()){
return nextMoves;
}
for(int row=0;row<3;row++){
for(int col=0;col<3;col++){
if(s[row][col]==" "){
nextMoves.add(new int[] {row,col});
}
}
}
return nextMoves;
}
boolean eval_A(){
if(s[0][0]==s[1][0]){
if(s[1][0]==s[2][0]){
if(s[1][0]=="X"){
return true;
}
}
}
if(s[0][0]==s[0][1]){
if(s[0][0]==s[0][2]){
if(s[0][0]=="X"){
return true;
}
}
}
if(s[1][0]==s[1][1]){
if(s[1][0]==s[1][2]){
if(s[1][0]=="X"){
return true;
}
}
}
if(s[2][0]==s[2][1]){
if(s[2][0]==s[2][2]){
if(s[2][0]=="X"){
return true;}
}
}
if(s[0][1]==s[1][1]){
if(s[1][1]==s[2][1]){
if(s[0][1]=="X"){
return true;
}
}
}
if(s[0][2]==s[1][2]){
if(s[1][2]==s[2][2]){
if(s[0][2]=="X"){
return true;
}
}
}
if(s[0][0]==s[1][1]){
if(s[1][1]==s[2][2]){
if(s[1][1]=="X"){
return true;
}
}
}
if(s[0][2]==s[1][1]){
if(s[1][1]==s[2][0]){
if(s[1][1]=="X"){
return true;
}
}
}
if(s[0][0]==s[1][0]){
if(s[1][0]==s[2][0]){
if(s[1][0]=="X"){
return true;
}
}
}
return false;
}
boolean eval_B(){
if(s[0][0]==s[0][1]){
if(s[0][0]==s[0][2]){
if(s[0][2]=="O"){
return true;
}
}
}
if(s[1][0]==s[1][1]){
if(s[1][0]==s[1][2]){
if(s[1][0]=="O"){
return true;
}
}
}
if(s[2][0]==s[2][1]){
if(s[2][0]==s[2][2]){
if(s[2][0]=="O"){
return true;
}
}
}
if(s[0][1]==s[1][1]){
if(s[1][1]==s[2][1]){
if(s[0][1]=="O"){
return true;
}
}
}
if(s[0][2]==s[1][2]){
if(s[1][2]==s[2][2]){
if(s[0][2]=="O"){
return true;
}
}
}
if(s[0][0]==s[1][1]){
if(s[1][1]==s[2][2]){
if(s[1][1]=="O"){
return true;
}
}
}
if(s[0][2]==s[1][1]){
if(s[1][1]==s[2][0]){
if(s[0][2]=="O"){
return true;
}
}
}
if(s[0][0]==s[1][0]){
if(s[1][0]==s[2][0]){
if(s[1][0]=="X"){
return true;
}
}
}
return false;
}
}
If you need AI player.then you need to study about how the minimax algorithm works before starts doing.I tried many from internet and try to keep simple as possible.
Sources:
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