Add Check for doesn't null map & visualMap elements

Board.java

@@ -5,6 +5,7 @@ import java.io.IOException;
  * @author Rezvanian 9831029
  * @version 0.0
  */
+
 public class Board implements IBoard  {
     private final int SIZE = 9;
     //for programmer
@@ -16,6 +17,7 @@ public class Board implements IBoard  {
      * This constructor, initialise the fields.
      */
     public Board(){
+
         map = new char[81];
         for (int i = 0; i < SIZE * SIZE; i++){
             switch (i){
@@ -71,7 +73,8 @@ public class Board implements IBoard  {
                     this.map[i] = '8';
                 }
                 default:{
-                    this.map[i] = ' ';
+                    if (this.map[i] != 'w' || this.map[i] != 'b')
+                        this.map[i] = ' ';
                 }
             }
         }
@@ -84,7 +87,8 @@ public class Board implements IBoard  {
                 }else if (yColumn % 8 == 0){
                     visualMap[xRow][yColumn] = '*';
                 } else {
-                    visualMap[xRow][yColumn] = ' ';
+                    if (this.visualMap[xRow][yColumn] != 'w' || this.visualMap[xRow][yColumn] != 'b')
+                        visualMap[xRow][yColumn] = ' ';
                 }
             }
             for (int i = 0; i <= 36; i++){
@@ -144,7 +148,7 @@ public class Board implements IBoard  {
     public void setVisualMapByPosition(int xPosition, int yPosition, char nut){
         xPosition = 8 * (xPosition - 1) + 4;
         yPosition = 4 * (yPosition - 1) + 2;
-        visualMap[yPosition][xPosition] = nut;
+        this.visualMap[yPosition][xPosition] = nut;
     }
 
     public int searchPosition(char c){