diff --git a/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java b/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java
index a64ae36..bcaa443 100644
--- a/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java
+++ b/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java
@@ -4,6 +4,7 @@
 import java.io.FileReader;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -1001,61 +1002,67 @@
 	public static ArrayList<Alias> findAllStartAlias(MethodExecution me) {
 		ArrayList<Alias> startAliasList = new ArrayList<>();
 		List<Statement> statements = me.getStatements();
+		String[] primitives = {"byte", "short", "int", "long", "float", "double", "char", "boolean"};
+		List<String> primitiveList = Arrays.asList(primitives);
 		for (int i = 0; i < statements.size(); i++) {
 			TracePoint tp = me.getTracePoint(i);
 			Statement statement = statements.get(i);
 			if (statement instanceof FieldAccess) {
 				FieldAccess fa = (FieldAccess)statement;
 				String objId = fa.getContainerObjId();
-				if (!("0".equals(objId))) {
-					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_CONTAINER));	
+				if (objId != null && !(objId.equals("0")) && !(primitiveList.contains(fa.getContainerClassName()))) {
+					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_CONTAINER));
 				}
 				objId = fa.getValueObjId();
-				if ((!"0".equals(objId))) {
-					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_FIELD));	
+				if (objId != null && !(objId.equals("0")) && !(primitiveList.contains(fa.getValueClassName()))) {
+					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_FIELD));
 				}
 			} else if (statement instanceof FieldUpdate) {
 				FieldUpdate fu = (FieldUpdate)statement;
 				String objId = fu.getContainerObjId();
-				if ((!"0".equals(objId))) {
-					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_CONTAINER));	
+				if (objId != null && !(objId.equals("0")) && !(primitiveList.contains(fu.getContainerClassName()))) {
+					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_CONTAINER));
 				}
 				objId = fu.getValueObjId();
-				if ((!"0".equals(objId))) {
-					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_FIELD));	
+				if (objId != null && !(objId.equals("0")) && !(primitiveList.contains(fu.getValueClassName()))) {
+					startAliasList.add(new Alias(objId, tp, Alias.OCCURRENCE_EXP_FIELD));
 				}
 			} else if (statement instanceof ArrayAccess) {
-				String valueObjId = ((ArrayAccess)statement).getValueObjectId();
-				if (!("0".equals(valueObjId))) {
-					startAliasList.add(new Alias(valueObjId, tp, Alias.OCCURRENCE_EXP_ARRAY));	
-				}
+				ArrayAccess aa = (ArrayAccess)statement;
+				String valueObjId = aa.getValueObjectId();
+				if (valueObjId != null && !(valueObjId.equals("0")) && !(primitiveList.contains(aa.getValueClassName()))) {
+					startAliasList.add(new Alias(valueObjId, tp, Alias.OCCURRENCE_EXP_ARRAY));
+				}				
 			} else if (statement instanceof ArrayUpdate) {
-				String valueObjId = ((ArrayUpdate)statement).getValueObjectId();
-				if (!("0".equals(valueObjId))) {
-					startAliasList.add(new Alias(valueObjId, tp, Alias.OCCURRENCE_EXP_ARRAY));	
+				ArrayUpdate au = (ArrayUpdate)statement;
+				String valueObjId = au.getValueObjectId();
+				if (valueObjId != null && !(valueObjId.equals("0")) && !(primitiveList.contains(au.getValueClassName()))) {
+					startAliasList.add(new Alias(valueObjId, tp, Alias.OCCURRENCE_EXP_ARRAY));
 				}
 			} else if (statement instanceof ArrayCreate) {
-				String valueObjId = ((ArrayAccess)statement).getValueObjectId();
-				if (!("0".equals(valueObjId))) {
-					startAliasList.add(new Alias(valueObjId, tp, Alias.OCCURRENCE_EXP_RETURN));	
+				ArrayCreate ac = (ArrayCreate)statement;
+				String arrayObjId = ac.getArrayObjectId();
+				if (arrayObjId != null && !(arrayObjId.equals("0")) && !(primitiveList.contains(ac.getArrayClassName()))) {
+					startAliasList.add(new Alias(arrayObjId, tp, Alias.OCCURRENCE_EXP_RETURN));
 				}
 			} else if (statement instanceof MethodInvocation) {
 				MethodExecution calledMe = ((MethodInvocation)statement).getCalledMethodExecution();
 				String thisObjId = calledMe.getThisObjId();
-				if (!("0".equals(thisObjId))) {
-					startAliasList.add(new Alias(thisObjId, tp, Alias.OCCURRENCE_EXP_RECEIVER));	
+				if (thisObjId != null && !(thisObjId.equals("0"))) {
+					startAliasList.add(new Alias(thisObjId, tp, Alias.OCCURRENCE_EXP_RECEIVER));
 				}
 				List<ObjectReference> args = calledMe.getArguments();
 				for (int j = 0; j < args.size(); j++) {
-					String argValueId = args.get(j).getId();
-					if (!("0".equals(argValueId))) {
-						startAliasList.add(new Alias(argValueId, tp, (j + Alias.OCCURRENCE_EXP_FIRST_ARG)));	
+					ObjectReference arg = args.get(j);
+					String argValueId = arg.getId();
+					if (argValueId != null && !(argValueId.equals("0")) && !(primitiveList.contains(arg.getActualType()))) {
+						startAliasList.add(new Alias(argValueId, tp, (j + Alias.OCCURRENCE_EXP_FIRST_ARG)));
 					}
 				}
 				ObjectReference returnValue = calledMe.getReturnValue();
 				if (returnValue != null) {
 					String returnValueId = returnValue.getId();
-					if (!("0".equals(returnValueId))) {
+					if (returnValueId != null && !(returnValueId.equals("0") && !(primitiveList.contains(returnValue.getActualType())))) {
 						startAliasList.add(new Alias(returnValueId, tp, Alias.OCCURRENCE_EXP_RETURN));
 					}
 				}