added everytime player change

src/de/itsblue/ConnectFour/ConnectFour.java

@@ -34,6 +34,8 @@ public class ConnectFour extends JFrame implements ActionListener {
 
     private ButtonRow buttonRow;
 
+    private int player = 0;
+
     /**
      * Constructor
      */
@@ -74,9 +76,16 @@ public class ConnectFour extends JFrame implements ActionListener {
      * @param column The column to insert the plate into
      */
     private void insertNextPlate(int column) {
-        // TODO: change player everytime
+        String res;
-        String res = this.gameBoard.insertPlate(new Plate(PlateType.X), column);
 
+
+
+        if (player == 0) {
+            res = this.gameBoard.insertPlate(new Plate(PlateType.X), column);
+        } else {
+            res = this.gameBoard.insertPlate(new Plate(PlateType.O), column);
+        }
+        
         if (res == "err") {
             // beep in case of error
             Toolkit.getDefaultToolkit().beep();
@@ -84,6 +93,22 @@ public class ConnectFour extends JFrame implements ActionListener {
             PlateType winnerType = PlateType.valueOf(res);
             System.out.println("A player won: " + winnerType);
         }
+        
+        switchPlayer();
+
+    }
+
+
+    /**
+     * Function to switch the player
+     */
+    private void switchPlayer() {
+        if (player == 0) {
+            player = 1;
+        }
+        else{
+            player = 0;
+        }
     }
 
     /**