trying to draw a red line through all winning entries

TicTacToe - MinMax/src/Game.java

@@ -1,36 +1,69 @@
 import javax.swing.*;
+import java.awt.*;
 
 public class Game {
 
-    int[] playfield;
+    private int[] playfield;
+    private boolean turnTaken = false;
+    private int winningX1,winningY1,winningX2,winningY2;
 
     public Game(){
         playfield = new int[9];
     }
 
-    public void place(int player, int position){
-        if (playfield[position] == -1){
+    public void place(int position, int player){
+        if (playfield[position] == 0){
             playfield[position] = player;
+            if (player == 1) {
+                turnTaken = true;
+            }
         } else {
-            JOptionPane.showConfirmDialog(null,"Tile is already taken");
+            JOptionPane.showInternalMessageDialog(null,"Tile is already taken");
+        }
+    }
+
+    public void computersTurn(){
+        boolean isPlaced = false;
+        try {
+            Thread.sleep(750);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        while(!isPlaced){
+            int random = (int) (Math.random() * (8 - 0 + 1) + 0);
+            System.out.println(random);
+                // if field is free
+                if (playfield[random] == 0) {
+                    place(random, -1);
+                    isPlaced = true;
+                }
         }
     }
 
     public boolean checkWin() {
+        //only check if winning is possible
         if (emptyTiles() < 5) {
             for (int i = 0; i < 3; i++) {
-                if ((playfield[i] == playfield[i + 3]) && (playfield[i] == playfield[i + 6])) {
-                    System.out.println("vertical");
+                //horizontal
+                if ((playfield[i] == playfield[i + 3] && playfield[i] != 0) && (playfield[i] == playfield[i + 6])) {
+                    winningX1 = 0;
+                    winningX2 = 3;
+                    winningY1 = winningY2 = i;
                     return true;
-                } else if ((playfield[i * 3] == playfield[i * 3 + 1]) && (playfield[i * 3] == playfield[i * 3 + 2])) {
-                    System.out.println("horizontal");
+                }
+                //vertical
+                else if ((playfield[i * 3] == playfield[i * 3 + 1] && playfield[i * 3] != 0) && (playfield[i * 3] == playfield[i * 3 + 2])) {
+                    winningX1 = winningX2 = i;
+                    winningY1 = 0;
+                    winningY2 = 3;
                     return true;
                 }
             }
-            return (playfield[2] == playfield[4]) && (playfield[2] == playfield[6]) || (playfield[0] == playfield[4]) && (playfield[0] == playfield[8]);
-        } else {
-            return false;
+            //diagonal
+            return (playfield[2] == playfield[4] && playfield[2] != 0) && (playfield[2] == playfield[6]) ||
+                    (playfield[0] == playfield[4] && playfield[0] != 0) && (playfield[0] == playfield[8]);
         }
+        return false;
     }
 
     public int emptyTiles(){
@@ -43,6 +76,14 @@ public class Game {
         return n;
     }
 
+    public boolean isTurnTaken() {
+        return turnTaken;
+    }
+
+    public void setTurnTaken(boolean turnTaken) {
+        this.turnTaken = turnTaken;
+    }
+
     public void setPlayfield(int position, int value) {
         playfield[position] = value;
     }
@@ -50,4 +91,20 @@ public class Game {
     public int[] getPlayfield() {
         return playfield;
     }
+
+    public int getWinningX1() {
+        return winningX1;
+    }
+
+    public int getWinningX2() {
+        return winningX2;
+    }
+
+    public int getWinningY1() {
+        return winningY1;
+    }
+
+    public int getWinningY2() {
+        return winningY2;
+    }
 }