diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java
index dd19cc1..ca40e05 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java
@@ -4,6 +4,7 @@
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 
@@ -19,6 +20,7 @@
 import models.algebra.Expression;
 import models.algebra.Field;
 import models.algebra.Parameter;
+import models.algebra.Position;
 import models.algebra.Symbol;
 import models.algebra.Term;
 import models.algebra.Type;
@@ -112,13 +114,13 @@
 				}
 			}
 			Set<ResourcePath> refs = new HashSet<>();
-			for (Channel cg : model.getChannels()) {
-				DataTransferChannel c = (DataTransferChannel) cg;
+			for (Channel ch : model.getChannels()) {
+				DataTransferChannel c = (DataTransferChannel) ch;
 				if (c.getInputResources().contains(rn.getResource())) {
-					for (ResourcePath id: c.getReferenceResources()) {
-						if (!refs.contains(id) && !depends.contains(id)) {
-							refs.add(id);
-							String refResName = id.getResourceName();
+					for (ResourcePath res: c.getReferenceResources()) {
+						if (!refs.contains(res) && !depends.contains(res)) {
+							refs.add(res);
+							String refResName = res.getResourceName();
 							fieldInitializer += refResName.toLowerCase() + ",";
 							f = true;
 						}
@@ -177,17 +179,17 @@
 			}
 			// Declare a field to refer to the reference resource.
 			refs = new HashSet<>();
-			for (Channel cg : model.getChannels()) {
-				DataTransferChannel c = (DataTransferChannel) cg;
+			for (Channel ch : model.getChannels()) {
+				DataTransferChannel c = (DataTransferChannel) ch;
 				if (c.getInputResources().contains(rn.getResource())) {
-					for (ResourcePath id: c.getReferenceResources()) {
-						if (!refs.contains(id) && !depends.contains(id)) {
-							refs.add(id);
-							String refResName = id.getResourceName();
+					for (ResourcePath res: c.getReferenceResources()) {
+						if (!refs.contains(res) && !depends.contains(res)) {
+							refs.add(res);
+							String refResName = res.getResourceName();
 							refResName = refResName.substring(0, 1).toUpperCase() + refResName.substring(1);
-							type.addField(new FieldDeclaration(new Type(refResName, refResName), id.getResourceName()));
-							constructor.addParameter(new VariableDeclaration(new Type(refResName, refResName), id.getResourceName()));						
-							block.addStatement("this." + id.getResourceName() + " = " + id.getResourceName() + ";");
+							type.addField(new FieldDeclaration(new Type(refResName, refResName), res.getResourceName()));
+							constructor.addParameter(new VariableDeclaration(new Type(refResName, refResName), res.getResourceName()));						
+							block.addStatement("this." + res.getResourceName() + " = " + res.getResourceName() + ";");
 						}
 					}
 				}
@@ -197,14 +199,31 @@
 				type.addMethod(constructor);
 			
 			// Declare input methods in resources and the main type.
-			for (Channel cg : model.getIOChannels()) {
-				for (ChannelMember cm : ((DataTransferChannel) cg).getOutputChannelMembers()) {
+			for (Channel ch : model.getIOChannels()) {
+				for (ChannelMember cm : ((DataTransferChannel) ch).getOutputChannelMembers()) {
 					if (cm.getResource().equals(rn.getResource())) {
 						Expression message = cm.getStateTransition().getMessageExpression();
-						if (message.getClass() == Term.class) {
+						if (message instanceof Term) {
 							ArrayList<VariableDeclaration> params = new ArrayList<>();
-							for (Variable var: message.getVariables().values()) {
-								params.add(new VariableDeclaration(var.getType(), var.getName()));
+							for (Map.Entry<Position, Variable> varEnt: message.getVariables().entrySet()) {
+								Variable var = varEnt.getValue();
+								String refVarName = null;
+								for (ChannelMember refCm: ((DataTransferChannel) ch).getReferenceChannelMembers()) {
+									Expression varExp = refCm.getStateTransition().getMessageExpression().getSubTerm(varEnt.getKey());
+									if (varExp != null && varExp instanceof Variable) {
+										if (refCm.getStateTransition().getCurStateExpression().contains(varExp)) {
+											refVarName = refCm.getResource().getResourceName();
+											break;
+										}
+									}
+								}
+								if (refVarName != null) {
+									// var has come from a reference resource.
+									params.add(new VariableDeclaration(var.getType(), refVarName));
+								} else {
+									// var has not come from reference resource.
+									params.add(new VariableDeclaration(var.getType(), var.getName()));
+								}
 							}
 							MethodDeclaration input = new MethodDeclaration(
 									((Term) cm.getStateTransition().getMessageExpression()).getSymbol().getImplName(),
@@ -227,7 +246,7 @@
 									}
 								}
 							}
-						} else if (message.getClass() == Variable.class) {
+						} else if (message instanceof Variable) {
 							MethodDeclaration input = new MethodDeclaration(
 									((Variable) cm.getStateTransition().getMessageExpression()).getName(),
 									false, typeVoid, null);
@@ -245,8 +264,8 @@
 			
 			// Declare the field to store the state in the type of each resource.
 			if (((StoreAttribute) rn.getAttribute()).isStored()) {
-				ResourcePath resId = rn.getResource();
-				type.addField(new FieldDeclaration(resId.getResourceStateType(), "value", getInitializer(resId)));
+				ResourcePath res = rn.getResource();
+				type.addField(new FieldDeclaration(res.getResourceStateType(), "value", getInitializer(res)));
 			}
 			
 			// Declare the getter method to obtain the state in the type of each resource.
@@ -325,16 +344,16 @@
 		return codes;
 	}
 
-	private static String getInitializer(ResourcePath resId) {
-		Type stateType = resId.getResourceStateType();
+	private static String getInitializer(ResourcePath res) {
+		Type stateType = res.getResourceStateType();
 		String initializer = null;
-		if (resId.getInitialValue() != null) {
-			initializer = resId.getInitialValue().toImplementation(new String[] {""});
+		if (res.getInitialValue() != null) {
+			initializer = res.getInitialValue().toImplementation(new String[] {""});
 		} else {
 			if (DataConstraintModel.typeList.isAncestorOf(stateType)) {
-				initializer = "new " + resId.getResourceStateType().getImplementationTypeName() + "()";
+				initializer = "new " + res.getResourceStateType().getImplementationTypeName() + "()";
 			} else if (DataConstraintModel.typeMap.isAncestorOf(stateType)) {
-				initializer = "new " + resId.getResourceStateType().getImplementationTypeName() + "()";
+				initializer = "new " + res.getResourceStateType().getImplementationTypeName() + "()";
 			}
 		}
 		return initializer;