Refactor Cell and subclasses

app/src/main/java/xl/model/BombCell.java

@@ -19,4 +19,7 @@ public class BombCell implements Cell {
         throw XLException.ERROR_RECURSIVE;
     }
     
+    public String formula() {
+        throw XLException.ERROR_RECURSIVE;
+    }
 }

app/src/main/java/xl/model/Cell.java

@@ -8,4 +8,5 @@ import xl.expr.Environment;
 public interface Cell {
     public double cellValue(Environment e);
     public String displayValue();
+    public String formula();
 }

app/src/main/java/xl/model/CommentCell.java

@@ -16,6 +16,10 @@ public class CommentCell implements Cell {
     }
 
     public String displayValue() {
+        return "# " + commentText;
+    }
+
+    public String formula() {
         return commentText;
     }
 }

app/src/main/java/xl/model/ExpressionCell.java

@@ -18,9 +18,12 @@ public class ExpressionCell implements Cell {
     }
 
     public String displayValue() {
+        return Double.toString(cellValue(ENVIRON));
+    }
+
+    public String formula() {
         return expr.toString();
     }
-    
 }
 
 

app/src/main/java/xl/model/XLModel.java

@@ -107,26 +107,17 @@ public class XLModel extends Observable implements Environment {
 
     public String getAddressValue(String address) {
         if (map.containsKey(address)) {
-            Cell cell = map.get(address);
+            return map.get(address).displayValue();
-            if (cell instanceof CommentCell) {
-                return cell.displayValue();
-            }
-            return Double.toString(cell.cellValue(this));
         }
         return "";
     }
 
     public String getAddressContent(String address) {
         if (map.containsKey(address)) {
-            Cell cell = map.get(address);
+            return map.get(address).formula();
-            if (cell instanceof CommentCell) {
-                return "#" + map.get(address).displayValue();
         }
-            return map.get(address).displayValue();
-        } else {
         return "";
     }
-    }
 
     public boolean containsKey(String address) {
         return map.containsKey(address);