extract duplicate code to a separate method

src/main/java/de/dhbwstuttgart/inferWildcards/ReplaceTypeparamVisitor.java

@@ -116,20 +116,14 @@ public class ReplaceTypeparamVisitor
 						// parent TPH mapping
 						this.visit(nextRefType);
 
-						// Generate TPH
+						generateTphAndReplaceInTree(listIterator, next);
-						TypePlaceholder tph = generateTypePlaceholder(nextRefType);
-
-						// Replace in AST
-						listIterator.set(tph);
 					}
 					else if (next instanceof GenericRefType) {
-						GenericRefType nextGenericRefType = (GenericRefType) next;
 
-						// Generate TPH
+						// Visit of nested type arguments not necessary as Generic Types cannot contain
-						TypePlaceholder tph = generateTypePlaceholder(nextGenericRefType);
+						// type parameters
 
-						// Replace in AST
+						generateTphAndReplaceInTree(listIterator, next);
-						listIterator.set(tph);
 					}
 				}
 
@@ -152,5 +146,26 @@ public class ReplaceTypeparamVisitor
 			tphMap.put(tph, t);
 			return tph;
 		}
+
+		/**
+		 * Generate the TPH for a {@link RefTypeOrTPHOrWildcardOrGeneric}, saves the
+		 * mapping and replaces the type by the type placeholder in the tree.
+		 * 
+		 * @param listIterator {@link ListIterator} over
+		 *                     {@link RefTypeOrTPHOrWildcardOrGeneric} representing the
+		 *                     tree to replace in
+		 * @param refType      {@link RefTypeOrTPHOrWildcardOrGeneric} to generate type
+		 *                     placeholder for and replace
+		 */
+		private void generateTphAndReplaceInTree (ListIterator<RefTypeOrTPHOrWildcardOrGeneric> listIterator,
+				RefTypeOrTPHOrWildcardOrGeneric refType) {
+			// Generate TPH
+			TypePlaceholder tph = generateTypePlaceholder(refType);
+
+			// Replace in AST
+			listIterator.set(tph);
+		}
+
 	}
+
 }