Make fields final if possible.

src/main/java/carcassonne/control/state/AbstractGameState.java

@@ -17,7 +17,7 @@
  */
 public abstract class AbstractGameState { // TODO (HIGH) [AI] separate human move states from AI moves?
 
-    private StateMachine stateMachine;
+    private final StateMachine stateMachine;
     protected GameSettings settings;
     protected ViewFacade views;
     protected Round round;

src/main/java/carcassonne/control/state/StateManning.java

@@ -17,7 +17,7 @@
  * @author Timur Saglam
  */
 public class StateManning extends AbstractGameState {
-    private boolean[] noMeeplesNotification;
+    private final boolean[] noMeeplesNotification;
 
     /**
      * Constructor of the state.

src/main/java/carcassonne/model/grid/GridPattern.java

@@ -22,8 +22,8 @@ public class GridPattern {
 
     private boolean disbursed;
     protected boolean complete;
-    private Map<Player, Integer> involvedPlayers;
-    private List<Meeple> meepleList;
+    private final Map<Player, Integer> involvedPlayers;
+    private final List<Meeple> meepleList;
     protected final TerrainType patternType;
     protected int scoreMultiplier;
     protected List<GridSpot> containedSpots;

src/main/java/carcassonne/view/main/MeepleLayer.java

@@ -22,12 +22,12 @@
  */
 public class MeepleLayer extends JPanel {
     private static final long serialVersionUID = -843137441362337953L;
-    private List<MeepleDepictionPanel> meeplePanels;
-    private MeepleDepictionPanel[][] meeplePanelGrid;
-    private JComponent[][] placeholderGrid;
+    private final List<MeepleDepictionPanel> meeplePanels;
+    private final MeepleDepictionPanel[][] meeplePanelGrid;
+    private final JComponent[][] placeholderGrid;
     private final List<RigidRectangle> placeholders;
     private int zoomLevel;
-    private ControllerFacade controller;
+    private final ControllerFacade controller;
 
     /**
      * Creates the meeple layer.

src/main/java/carcassonne/view/main/TileLayer.java

@@ -21,8 +21,8 @@
 public class TileLayer extends JPanel {
     private static final long serialVersionUID = 1503933201337556131L;
     private final List<TileDepiction> placementHighlights;
-    private List<TileDepiction> tileLabels;
-    private TileDepiction[][] tileDepictionGrid;
+    private final List<TileDepiction> tileLabels;
+    private final TileDepiction[][] tileDepictionGrid;
 
     /**
      * Creates the tile layer.