Use isEmpty().
diff --git a/src/main/java/org/apache/commons/scxml2/io/ModelUpdater.java b/src/main/java/org/apache/commons/scxml2/io/ModelUpdater.java
index b5b5815..b579cc3 100644
--- a/src/main/java/org/apache/commons/scxml2/io/ModelUpdater.java
+++ b/src/main/java/org/apache/commons/scxml2/io/ModelUpdater.java
@@ -257,7 +257,7 @@
         }
 
         final List<History> histories = state.getHistory();
-        if (histories.size() > 0 && state.isSimple()) {
+        if (!histories.isEmpty() && state.isSimple()) {
             logAndThrowModelError(ERR_HISTORY_SIMPLE_STATE,
                     new Object[] {getName(state)});
         }
diff --git a/src/main/java/org/apache/commons/scxml2/io/SCXMLWriter.java b/src/main/java/org/apache/commons/scxml2/io/SCXMLWriter.java
index 07e084e..08f5b9e 100644
--- a/src/main/java/org/apache/commons/scxml2/io/SCXMLWriter.java
+++ b/src/main/java/org/apache/commons/scxml2/io/SCXMLWriter.java
@@ -683,7 +683,7 @@
     private static void writeOnEntry(final XMLStreamWriter writer, final OnEntry onentry)
             throws XMLStreamException {
 
-        if (onentry != null && (onentry.isRaiseEvent() || onentry.getActions().size() > 0 )) {
+        if (onentry != null && (onentry.isRaiseEvent() || !onentry.getActions().isEmpty() )) {
             writer.writeStartElement(SCXMLConstants.ELEM_ONENTRY);
             writeAV(writer, SCXMLConstants.ATTR_EVENT, onentry.getRaiseEvent());
             writeExecutableContent(writer, onentry.getActions());
@@ -702,7 +702,7 @@
     private static void writeOnExit(final XMLStreamWriter writer, final OnExit onexit)
             throws XMLStreamException {
 
-        if (onexit != null && (onexit.isRaiseEvent() || onexit.getActions().size() > 0)) {
+        if (onexit != null && (onexit.isRaiseEvent() || !onexit.getActions().isEmpty())) {
             writer.writeStartElement(SCXMLConstants.ELEM_ONEXIT);
             writeAV(writer, SCXMLConstants.ATTR_EVENT, onexit.getRaiseEvent());
             writeExecutableContent(writer, onexit.getActions());
@@ -773,7 +773,7 @@
     private static void writeFinalize(final XMLStreamWriter writer, final Finalize finalize)
             throws XMLStreamException {
 
-        if (finalize != null && finalize.getActions().size() > 0) {
+        if (finalize != null && !finalize.getActions().isEmpty()) {
             writer.writeStartElement(SCXMLConstants.ELEM_FINALIZE);
             writeExecutableContent(writer, finalize.getActions());
             writer.writeEndElement();
diff --git a/src/main/java/org/apache/commons/scxml2/model/SimpleTransition.java b/src/main/java/org/apache/commons/scxml2/model/SimpleTransition.java
index 25ba72f..5574ded 100644
--- a/src/main/java/org/apache/commons/scxml2/model/SimpleTransition.java
+++ b/src/main/java/org/apache/commons/scxml2/model/SimpleTransition.java
@@ -159,7 +159,7 @@
             // derive typeInternal
             typeInternal = TransitionType.internal == type && isCompoundStateParent(getParent());
 
-            if (typeInternal && targets.size() > 0) {
+            if (typeInternal && !targets.isEmpty()) {
                 for (final TransitionTarget tt : targets) {
                     if (!tt.isDescendantOf(getParent())) {
                         typeInternal = false;
@@ -195,7 +195,7 @@
      */
     public TransitionalState getTransitionDomain() {
         TransitionalState ts = transitionDomain;
-        if (ts == null && targets.size() > 0 && !scxmlTransitionDomain) {
+        if (ts == null && !targets.isEmpty() && !scxmlTransitionDomain) {
 
             if (getParent() != null) {
                 if (isTypeInternal()) {