Add javadocs to important fields

src/main/java/org/terasology/metalrenegades/economy/ui/TradingScreen.java

@@ -38,6 +38,9 @@ public class TradingScreen extends CoreScreenLayer {
     @In
     private NUIManager nuiManager;
 
+    /**
+     * UI Elements
+     */
     private UIList<MarketItem> pList;
     private UIList<MarketItem> cList;
     private UIButton confirm;
@@ -46,12 +49,21 @@ public class TradingScreen extends CoreScreenLayer {
     private UILabel pCost;
     private UILabel cCost;
 
+    /**
+     * Information for UILists
+     */
     private List<MarketItem> pItems = new ArrayList<>();
     private List<MarketItem> cItems = new ArrayList<>();
 
+    /**
+     * Selected items
+     */
     private MarketItem pSelected = MarketItemBuilder.getEmpty();
     private MarketItem cSelected = MarketItemBuilder.getEmpty();
 
+    /**
+     * Trade result message
+     */
     private String message;
 
     @Override

src/main/java/org/terasology/metalrenegades/economy/ui/TradingUISystem.java

@@ -68,12 +68,22 @@ public class TradingUISystem extends BaseComponentSystem {
     @In
     private BlockCommands blockCommands;
 
-    private final int PROBABILITY = 50;
+    /**
+     * Maximum percentage difference between two values for them to be considered about equal
+     */
     private final int MARGIN_PERCENTAGE = 20;
 
-    private TradingScreen tradingScreen;
+    /**
+     * Probability that a trade will be accepted, provided the costs are about equal
+     */
+    private final int PROBABILITY = 50;
+
+    /**
+     * Citizen entity that the player is trading with
+     */
     private EntityRef targetCitizen = EntityRef.NULL;
 
+    private TradingScreen tradingScreen;
     private Logger logger = LoggerFactory.getLogger(TradingUISystem.class);
 
     @Override