diff --git a/README.md b/README.md
index 3b88b89..9675f6b 100644
--- a/README.md
+++ b/README.md
@@ -4,3 +4,6 @@ a JSON serializer based on bytecode manipulation
 * creates a Json serializer for a java type using javassist
 * deserializing not yet implemented
 * see the unit tests to see how it works
+
+
+* as of java9 it needs `--add-opens java.base/java.lang=ALL-UNNAMED` as java commandline option.
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index dfe5682..57427d9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,47 +15,21 @@
     </properties>
 
     <dependencies>
-        <dependency>
-            <groupId>commons-io</groupId>
-            <artifactId>commons-io</artifactId>
-            <version>2.6</version>
-        </dependency>
-
         <dependency>
             <groupId>org.javassist</groupId>
             <artifactId>javassist</artifactId>
             <version>3.26.0-GA</version>
         </dependency>
-
-        <dependency>
-            <groupId>ch.qos.logback</groupId>
-            <artifactId>logback-core</artifactId>
-            <version>1.2.3</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-api</artifactId>
-            <version>1.7.30</version>
-        </dependency>
-
-        <dependency>
-            <groupId>ch.qos.logback</groupId>
-            <artifactId>logback-classic</artifactId>
-            <version>1.2.3</version>
-        </dependency>
-
-
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>[4.13.1,)</version>
+            <version>4.13.2</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
-            <version>1.6.0</version>
+            <version>3.23.1</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -68,8 +42,21 @@
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
-            <version>2.10.5.1</version>
+            <version>2.15.1</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <argLine>--add-opens java.base/java.lang=ALL-UNNAMED</argLine>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 </project>
diff --git a/src/main/java/nl/jssl/jsontoy/serialize/JSONSerializer.java b/src/main/java/nl/jssl/jsontoy/serialize/JSONSerializer.java
index 6cc95b3..fd6ee54 100644
--- a/src/main/java/nl/jssl/jsontoy/serialize/JSONSerializer.java
+++ b/src/main/java/nl/jssl/jsontoy/serialize/JSONSerializer.java
@@ -11,9 +11,9 @@ public abstract class JSONSerializer<T> {
         if (object == null) {
             return "";
         } else if (object instanceof Number || object instanceof Boolean) {
-            return "" + object.toString();
+            return "" + object;
         } else if (object instanceof CharSequence || object instanceof Character) {
-            return "\"" + object.toString() + "\"";
+            return "\"" + object + "\"";
         } else {
             return handle(object);
         }
diff --git a/src/main/java/nl/jssl/jsontoy/serialize/SynthSerializerFactory.java b/src/main/java/nl/jssl/jsontoy/serialize/SynthSerializerFactory.java
index 5afc7b4..bf0daaf 100644
--- a/src/main/java/nl/jssl/jsontoy/serialize/SynthSerializerFactory.java
+++ b/src/main/java/nl/jssl/jsontoy/serialize/SynthSerializerFactory.java
@@ -1,5 +1,6 @@
 package nl.jssl.jsontoy.serialize;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -36,7 +37,7 @@ class SynthSerializerFactory {
     private static final String SET = "java.util.Set";
     private static final String MAP = "java.util.Map";
 
-    private static final Map<String, JSONSerializer<?>> serializers = new HashMap<>();
+    private static final Map<Class<?>, JSONSerializer<?>> serializers = new HashMap<>();
     private static final String ROOT_PACKAGE = "serializer.";
 
     private final ClassPool pool = ClassPool.getDefault();
@@ -55,37 +56,29 @@ class SynthSerializerFactory {
         }
     }
 
-     <T> JSONSerializer<T> createSerializer(Class<T> beanjavaClass) {
+    @SuppressWarnings("unchecked")
+    <T> JSONSerializer<T> createSerializer(Class<T> beanjavaClass) {
+        if (serializers.containsKey(beanjavaClass)) {
+            return (JSONSerializer<T>) serializers.get(beanjavaClass);
+        }
         try {
             CtClass beanClass = pool.get(beanjavaClass.getName());
-
-            return createSerializer2(beanClass);
-        } catch (NotFoundException e) {
+            return tryCreateSerializer(beanjavaClass, beanClass);
+        } catch (NotFoundException | CannotCompileException | InstantiationException | IllegalAccessException |
+                 InvocationTargetException | NoSuchMethodException e) {
             throw new SerializerCreationException(e);
         }
     }
 
-    @SuppressWarnings("unchecked")
-    private <T> JSONSerializer<T> createSerializer2(CtClass beanClass) {
-        if (serializers.containsKey(createSerializerName(beanClass))) {
-            return (JSONSerializer<T>) serializers.get(createSerializerName(beanClass));
-        }
-        try {
-            return tryCreateSerializer(beanClass);
-        } catch (NotFoundException | CannotCompileException | InstantiationException | IllegalAccessException e) {
-            throw new SerializerCreationException(e);
-        }
-    }
-
-    private <T> JSONSerializer<T> tryCreateSerializer(CtClass beanClass) throws NotFoundException, CannotCompileException, InstantiationException,
-            IllegalAccessException {
+    private <T> JSONSerializer<T> tryCreateSerializer(Class<?> javaClass, CtClass beanClass) throws NotFoundException, CannotCompileException, InstantiationException,
+            IllegalAccessException, InvocationTargetException, NoSuchMethodException {
         CtClass serializerClass = pool.makeClass(createSerializerName(beanClass), serializerBase);
 
         addToJsonStringMethod(beanClass, serializerClass);
 
         JSONSerializer<T> jsonSerializer = createSerializerInstance(serializerClass);
 
-        serializers.put(createSerializerName(beanClass), jsonSerializer);
+        serializers.put(javaClass, jsonSerializer);
         return jsonSerializer;
     }
 
@@ -99,16 +92,16 @@ class SynthSerializerFactory {
     /*
      * Creates the source, handling the for JSON different types of classes
      */
-    private <T> String createToJSONStringMethodSource(CtClass beanClass) throws NotFoundException {
+    private String createToJSONStringMethodSource(CtClass beanClass) throws NotFoundException {
         String source = "public String handle(Object object){\n";
         if (beanClass.isArray()) {
             source += "\tObject[] array=(Object[])object;\n";
-            source += handleArray(beanClass);
+            source += handleArray();
         } else if (isCollection(beanClass)) {
             source += "\tObject[] array=((java.util.Collection)object).toArray();\n";
-            source += handleArray(beanClass);
+            source += handleArray();
         } else if (isMap(beanClass)) {
-            source += handleMap(beanClass);
+            source += handleMap();
         } else if (!isPrimitiveOrWrapperOrString(beanClass)) {
             List<CtMethod> getters = getGetters(beanClass);
             if (shouldAddGetterCallers(getters)) {
@@ -117,18 +110,17 @@ class SynthSerializerFactory {
         } else {
             source += "\treturn \"\";}";
         }
-        System.out.println(source);
         return source;
     }
 
     /*
      * Any Collection is converted to an array, after which code is generated to handle the single elements.
-     * 
+     *
      * A subserializer is created for every single element, but most of the time it will be the same cached instance.
-     * 
+     *
      * The generated code fills a StringBuilder. The values are generated by the subserializers
      */
-    private String handleArray(CtClass beanClass) {
+    private String handleArray() {
         String source = "\tStringBuilder result=new StringBuilder(\"[\");\n";
         source += "\tfor (int i=0; i<array.length; i++){\n";
         source += "\t\tresult.append(" + Serializer.class.getName() + ".toJSONString(array[i]));\n";
@@ -141,7 +133,7 @@ class SynthSerializerFactory {
         return source;
     }
 
-    private String handleMap(CtClass beanClass) {
+    private String handleMap() {
         String source = "StringBuilder result=new StringBuilder(\"{\");\n";
         source += "\tfor (java.util.Iterator entries=((java.util.Map)object).entrySet().iterator();entries.hasNext();){\n";
         source += "\t\tjava.util.Map.Entry entry=(java.util.Map.Entry)entries.next();\n";
@@ -160,7 +152,7 @@ class SynthSerializerFactory {
     /*
      * If the class contains fields for which public getters are available, then these will be called in the generated code.
      */
-    private String addGetterCallers(CtClass beanClass, String source, List<CtMethod> getters) throws NotFoundException {
+    private String addGetterCallers(CtClass beanClass, String source, List<CtMethod> getters) {
         int index = 0;
         source += "\treturn ";
         source += "\"{";
@@ -176,13 +168,13 @@ class SynthSerializerFactory {
 
     @SuppressWarnings("unchecked")
     private <T> JSONSerializer<T> createSerializerInstance(CtClass serializerClass) throws InstantiationException, IllegalAccessException,
-            CannotCompileException {
-        return (JSONSerializer<T>) serializerClass.toClass().newInstance();
+            CannotCompileException, NoSuchMethodException, InvocationTargetException {
+        return (JSONSerializer<T>) serializerClass.toClass().getConstructor().newInstance();
     }
 
     /*
      * custom root package is prepended to avoid the java.lang class in which it's illegal to create new classes
-     * 
+     *
      * Array marks ( '[]' ) are replaced by the 'Array', Otherwise the SerializerClassName would be syntactically incorrect
      */
     public String createSerializerName(CtClass beanClass) {
@@ -218,7 +210,7 @@ class SynthSerializerFactory {
     /*
      * The JSON vernacular for key:value is pair...
      */
-    private String addPair(CtClass classToSerialize, String source, CtMethod getter) throws NotFoundException {
+    private String addPair(CtClass classToSerialize, String source, CtMethod getter) {
         source += jsonKey(getter);
         source += ": "; // what is the rule when it comes to spaces in json?
         source += jsonValue(classToSerialize, getter);
@@ -232,20 +224,14 @@ class SynthSerializerFactory {
         return "\\\"" + toFieldName(getter.getName()) + "\\\"";
     }
 
-    private String jsonValue(CtClass classToSerialize, CtMethod getter) throws NotFoundException {
-        String source = "";
-        CtClass returnType = getter.getReturnType();
-
+    private String jsonValue(CtClass classToSerialize, CtMethod getter) {
         /* primitives are wrapped so the produced methods adhere to the JSONSerializer interface */
-        source = createSubSerializerForReturnTypeAndAddInvocationToSource(classToSerialize, getter, source, returnType);
-
-        return source;
+        return createSubSerializerForReturnTypeAndAddInvocationToSource(classToSerialize, getter);
     }
 
-    private String createSubSerializerForReturnTypeAndAddInvocationToSource(CtClass classToSerialize, CtMethod getter, String source, CtClass returnType) {
+    private String createSubSerializerForReturnTypeAndAddInvocationToSource(CtClass classToSerialize, CtMethod getter) {
         /* NB there does not seem to be auto(un))boxing nor generic types (or other jdk1.5 stuff) in javassist compileable code */
-
-        source += "\"+" + Serializer.class.getName() + ".toJSONString(";
+        String source = "\"+" + Serializer.class.getName() + ".toJSONString(";
 
         // cast because of lack of generics
         source += "(" + cast(regularClassname(classToSerialize.getName())) + "object)." + getter.getName() + "()";
@@ -331,22 +317,22 @@ class SynthSerializerFactory {
 
     String asPrimitive(String name) {
         switch (name) {
-        case "int":
-            return "I";
-        case "byte":
-            return "B";
-        case "float":
-            return "F";
-        case "long":
-            return "J";
-        case "boolean":
-            return "Z";
-        case "char":
-            return "C";
-        case "double":
-            return "D";
-        case "short":
-            return "S";
+            case "int":
+                return "I";
+            case "byte":
+                return "B";
+            case "float":
+                return "F";
+            case "long":
+                return "J";
+            case "boolean":
+                return "Z";
+            case "char":
+                return "C";
+            case "double":
+                return "D";
+            case "short":
+                return "S";
         }
         return "";
     }
diff --git a/src/test/java/nl/jssl/jsontoy/serialize/performance/Jackson.java b/src/test/java/nl/jssl/jsontoy/serialize/performance/JacksonComparisonTest.java
similarity index 70%
rename from src/test/java/nl/jssl/jsontoy/serialize/performance/Jackson.java
rename to src/test/java/nl/jssl/jsontoy/serialize/performance/JacksonComparisonTest.java
index 56a5336..8daaa5b 100644
--- a/src/test/java/nl/jssl/jsontoy/serialize/performance/Jackson.java
+++ b/src/test/java/nl/jssl/jsontoy/serialize/performance/JacksonComparisonTest.java
@@ -13,50 +13,49 @@ import org.junit.Test;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
-public class Jackson {
-    List<String> trashbin = new ArrayList<String>();
+public class JacksonComparisonTest {
+    private static final int ITERATIONS = 20;
+    private static final int INNERLOOP_COUNT = 100000;
+    List<String> trashbin = new ArrayList<>();
 
     @Test
-    public void jackson() throws JsonProcessingException {
+    public void testPerformance() throws JsonProcessingException {
+        System.out.println("jackson,jsontoy");
         ObjectMapper objectMapper = new ObjectMapper();
         Bean1 bean1 = new Bean1();
         Bean2 bean2 = new Bean2();
         bean1.setData1(UUID.randomUUID().toString());
         bean1.setBean2(bean2);
         bean2.setData2(UUID.randomUUID().toString());
-        String valueAsString = objectMapper.writeValueAsString(bean1);
-        String jsonString = Serializer.toJSONString(bean1);
+        String valueAsString;
+        String jsonString;
 
-        for (int c = 0; c < 20; c++) {
+        for (int c = 0; c < ITERATIONS; c++) {
             trashbin.clear();
-            System.gc();
             long t0 = System.currentTimeMillis();
-            for (int i = 0; i < 100000; i++) {
+            for (int i = 0; i < INNERLOOP_COUNT; i++) {
                 bean1 = new Bean1();
                 bean2 = new Bean2();
                 bean1.setData1(UUID.randomUUID().toString());
                 bean1.setBean2(bean2);
                 bean2.setData2(UUID.randomUUID().toString());
                 valueAsString = objectMapper.writeValueAsString(bean1);
-                // System.out.println(valueAsString);
                 trashbin.add(valueAsString);
             }
-            System.out.print(System.currentTimeMillis() - t0);
+            System.out.printf("% 7d",(System.currentTimeMillis() - t0));
             System.out.print(",");
             trashbin.clear();
-            System.gc();
             long tt0 = System.currentTimeMillis();
-            for (int i = 0; i < 100000; i++) {
+            for (int i = 0; i < INNERLOOP_COUNT; i++) {
                 bean1 = new Bean1();
                 bean2 = new Bean2();
                 bean1.setData1(UUID.randomUUID().toString());
                 bean1.setBean2(bean2);
                 bean2.setData2(UUID.randomUUID().toString());
                 jsonString = Serializer.toJSONString(bean1);
-                // System.out.println(jsonString);
                 trashbin.add(jsonString);
             }
-            System.out.println(System.currentTimeMillis() - tt0);
+            System.out.printf("% 7d%n",System.currentTimeMillis() - tt0);
         }
 
     }