diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/CodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/CodeGenerator.java
index daf30a2..9f1f26a 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/CodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/CodeGenerator.java
@@ -72,8 +72,10 @@
 			codes.add("public class " + type.getTypeName() + "{");
 			for (FieldDeclaration field : type.getFields()) {
 				if (type.getTypeName() != "Main") {
-					codes.add("\t" + "private " + field.getType().getImplementationTypeName() + " " + field.getName()
-							+ ";");
+					String cons = "\t" + "private " + field.getType().getImplementationTypeName() + " " + field.getName();
+					if(field.getType().equals(DataConstraintModel.typeList)) cons += " = new ArrayList<>()";
+					cons += ";";
+					codes.add(cons);
 				} else {
 					String cons = "\t" + "private " + field.getType().getImplementationTypeName() + " "
 							+ field.getName() + " = new " + field.getType().getTypeName() + "(";
@@ -110,9 +112,9 @@
 						}
 					}
 					codes.add("\t" + "}");
+					codes.add("");
 				}
 			}
-			codes.add("");
 			for (MethodDeclaration method : type.getMethods()) {
 				String varstr = "\t" + "public " + method.getReturnType().getImplementationTypeName() + " "
 						+ method.getName() + "(";