refactorings and it is npos possible to create a new game at sandbox and then load them with the menu bar load new game for all difficulties. its even possible to walk through the games of that difficulty with next button. this button is queuing

src/main/java/src/GameField.java

@@ -122,8 +122,14 @@ public class GameField extends JPanel {
     public void setValue(int x, int y, int value) {
 
         JLabel jLabel = gameField[y][x].getjLabel();
-        jLabel.setText(String.valueOf(value));
-        jLabel.setVisible(true);
+
+        if (value <= 0) {
+            jLabel.setText("0");
+            jLabel.setVisible(false);
+        } else {
+            jLabel.setText(String.valueOf(value));
+            jLabel.setVisible(true);
+        }
 
     }
 

src/main/java/src/MainFrame.java

@@ -19,6 +19,8 @@ public class MainFrame extends JFrame {
 
     private JSONArray currentGameDifficulty;
     private Model currentModel;
+    private JLabel currentGameLabel;
+    private int currentPosition;
 
     public void run() {
 
@@ -79,10 +81,37 @@ public class MainFrame extends JFrame {
 
         JButton back = new JButton();
         back.setVisible(true);
-        back.setBounds(5, 5, 100, 25);
+        back.setBounds(120, 525, 100, 25);
         rootPanel.add(back);
         back.setText("Back");
 
+        currentGameLabel = new JLabel();
+        currentGameLabel.setVisible(true);
+        currentGameLabel.setBounds(250, 525, 40, 25);
+        currentGameLabel.setText("0/0");
+        rootPanel.add(currentGameLabel);
+
+        JButton next = new JButton();
+        next.setVisible(true);
+        next.setBounds(280, 525, 100, 25);
+        rootPanel.add(next);
+        next.setText("Next");
+        next.addActionListener(new ActionListener() {
+            @Override
+            public void actionPerformed(ActionEvent e) {
+
+                if (currentPosition+1 < currentGameDifficulty.size()) {
+                    currentPosition++;
+                } else {
+                    currentPosition = 0;
+                }
+                JSONObject jsonObject = (JSONObject) currentGameDifficulty.get(currentPosition);
+                loadDataToGameField(jsonObject);
+
+                currentGameLabel.setText((currentPosition+1)+"/"+currentGameDifficulty.size());
+            }
+        });
+
         JButton newButton  = new JButton();
         newButton.setVisible(true);
         newButton.setBounds(395, 5, 100, 25);
@@ -206,11 +235,46 @@ public class MainFrame extends JFrame {
                 }
                 currentGameDifficulty = (JSONArray) object.get("easyGame");
                 loadDataToGameField((JSONObject) currentGameDifficulty.get(0));
+                currentPosition = 0;
+                currentGameLabel.setText((currentPosition+1)+"/"+currentGameDifficulty.size());
             }
         });
 
         JMenuItem menu_i5=new JMenuItem("Mittel");
+        menu_i5.addActionListener(new ActionListener() {
+            @Override
+            public void actionPerformed(ActionEvent e) {
+                String data = Model.loadAllData();
+                JSONObject object = null;
+                try {
+                    object = (JSONObject)new JSONParser().parse(data);
+                } catch (ParseException ex) {
+                    throw new RuntimeException(ex);
+                }
+                currentGameDifficulty = (JSONArray) object.get("mediumGame");
+                loadDataToGameField((JSONObject) currentGameDifficulty.get(0));
+                currentPosition = 0;
+                currentGameLabel.setText((currentPosition+1)+"/"+currentGameDifficulty.size());
+            }
+        });
+
         JMenuItem menu_i6=new JMenuItem("Schwer");
+        menu_i6.addActionListener(new ActionListener() {
+            @Override
+            public void actionPerformed(ActionEvent e) {
+                String data = Model.loadAllData();
+                JSONObject object = null;
+                try {
+                    object = (JSONObject)new JSONParser().parse(data);
+                } catch (ParseException ex) {
+                    throw new RuntimeException(ex);
+                }
+                currentGameDifficulty = (JSONArray) object.get("hardGame");
+                loadDataToGameField((JSONObject) currentGameDifficulty.get(0));
+                currentPosition = 0;
+                currentGameLabel.setText((currentPosition+1)+"/"+currentGameDifficulty.size());
+            }
+        });
 
         m_menu.add(menu_i1);
         m_menu.add(menu_i2);

src/main/java/src/Model.java

@@ -207,7 +207,7 @@ public class Model {
                 JSONObject jsonObject = new JSONObject();
                 jsonObject.put("x", j);
                 jsonObject.put("y", i);
-                jsonObject.put("value", getField(i, j));
+                jsonObject.put("value", getField(j, i));
                 values.add(jsonObject);
 
             }

src/main/java/src/SandboxFrame.java

@@ -23,7 +23,6 @@ public class SandboxFrame extends JFrame {
         this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
 
         setupLayout();
-
     }
 
     private void setupLayout() {
@@ -58,6 +57,7 @@ public class SandboxFrame extends JFrame {
     }
 
     private JButton setupSaveButton() {
+
         JButton save = new JButton("Save");
         save.setVisible(true);
 
@@ -72,6 +72,7 @@ public class SandboxFrame extends JFrame {
 
             }
         });
+
         return save;
     }
 

src/test/java/ModelTest.java

@@ -46,6 +46,7 @@ public class ModelTest extends MainFrame {
                 "8 |  8 8 8   8 8 8   8 8 8\n";
 
 
+
         assertEquals(model.toString(), staticCase, "tested Overridden toString of Model.class");
     }
 
@@ -247,7 +248,7 @@ public class ModelTest extends MainFrame {
         GameField gameField = new GameField(360);
         for (int i = 0, k = 13; i < 9; i++) {
             for (int j = 0, l = 17; j < 9; j++) {
-                gameField.setValue(i, j, (i*l+j*k)%9);
+                gameField.setValue(j, i, (i*l+j*k)%9);
             }
         }
         Model model = new Model(gameField);
@@ -273,7 +274,7 @@ public class ModelTest extends MainFrame {
         GameField gf = new GameField(360);
         for (int i = 0, k = 13; i < 9; i++) {
             for (int j = 0, l = 17; j < 9; j++) {
-                gf.setValue(i, j, (i*l+j*k)%9);
+                gf.setValue(j, i, (i*l+j*k)%9);
             }
         }
         Model m = new Model(gf);