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I get a SerializationException at my GWT app. I was already looking for it on stackoverflow, but I don't find my mistake. I checked my classes for all points mentioned in this thread - I just can't find my mistake. Any Ideas what is wrong?

Here is the Tomcat-Error log:

Mär 13, 2014 2:40:07 PM org.apache.catalina.core.ApplicationContext log
SEVERE: Exception while dispatching incoming RPC call
com.google.gwt.user.client.rpc.SerializationException: Type 'test.shared.params.SelectParameter' was not included in the set of types which can be serialized by this SerializationPolicy or its Class object could not be loaded. For security purposes, this type will not be serialized.: instance = test.shared.params.SelectParameter@376b030f
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:667)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:44)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:39)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:51)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:28)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:788)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:587)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:757)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:796)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:44)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:39)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:51)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:28)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:788)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:587)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:757)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:796)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:44)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:39)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:51)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:28)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:788)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:587)
    at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:605)
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:471)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:563)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

Here is my abstract class:

public abstract class Parameter implements IsSerializable {

    private List<Condition> conditions;
    private boolean isMultipleParameter;
    private String predefinedTitle;
    private Map<String, String> helpText;
    private int typID;

    public Parameter() {
        super();
    }

    protected Parameter(List<Condition> conditions, boolean isMultipleParameter, String predefinedTitle, Map<String, String> helpText, int typID) {
        super();
        this.conditions = conditions;
        this.isMultipleParameter = isMultipleParameter;
        this.predefinedTitle = predefinedTitle;
        this.helpText = helpText;
        this.typID = typID;
    }
    // getter and setter
}

Here is the class where the error occours:

public class SelectParameter extends Parameter {

    private String defaultValue; // Default Value of this Parameter
    private List<String> valueList; // Value-Pool

    public SelectParameter() {
        super();
    }

    public SelectParameter(int typID, String defaultValue, List<Condition> conditionList, boolean isMultipleParameter, String predefinedTitle, Map<String, String> helpText) {
        super(conditionList, isMultipleParameter, predefinedTitle, helpText, typID);
        this.defaultValue = defaultValue;
        this.valueList = new ArrayList<>();
    }
    // getter and setter
}

web.xml file

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
              http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         version="2.5"
         xmlns="http://java.sun.com/xml/ns/javaee">

  <!-- Servlets -->
  <servlet>
    <servlet-name>greetServlet</servlet-name>
    <servlet-class>test.server.GreetingServiceImpl</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>greetServlet</servlet-name>
    <url-pattern>/test/greet</url-pattern>
  </servlet-mapping>

  <!-- Default page to serve -->
  <welcome-file-list>
    <welcome-file>Test.html</welcome-file>
  </welcome-file-list>

</web-app>

edit: 

public class Condition implements IsSerializable{

    private String parameterTitle;
    private List<String> valueList;

    public Condition(String parameterTitle) {
        super();
        this.parameterTitle = parameterTitle;
        this.valueList = new ArrayList<String>();
    }

    public Condition(){
        super();
    }
    // getter and setter
}
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Armin
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    Is 'Condition' serializable? – Andrei Volgin Mar 13 '14 at 14:44
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    Set the visibility of constructor in `Parameter` class to public. – Jiri Kremser Mar 13 '14 at 14:45
  • @JiriKremser only of the constructor without any parameters or all? – Armin Mar 13 '14 at 14:52
  • @Armin yes to your question. http://www.gwtproject.org/doc/latest/DevGuideServerCommunication.html#DevGuideSerializableTypes – Churro Mar 13 '14 at 14:56
  • @Churro yes to what? only the default constructor? or all constructors? – Armin Mar 13 '14 at 14:59
  • @Armin sorry. Make your default constructor public. See the "Serializable User-defined Classes" section of my link. To summarize, each class must have a default no-arg constructor that's public, any types you reference must themselves be serializable, and your class must directly or indirectly implement `Serializable` or GWT's `isSerializable`. – Churro Mar 13 '14 at 15:02
  • @Churro I changed it like you said. see above, I updated the changes in my question, same error – Armin Mar 13 '14 at 15:08
  • @Armin can you make sure ALL the bullet points are met on the links I gave you? This means you must look through the class that's causing the error, and its subclasses. Also, can you change `this.valueList = new ArrayList<>();` in `SelectParameter` to say `this.valueList = new ArrayList();` (add the generic type to ArrayList)? The last time I experienced this error, it was a minor mistake in one of my subclasses. – Churro Mar 13 '14 at 15:15
  • oh, yes... i have already read that GWT doesn't support java 7, but I didn't thought about it. It was the diamond operator who made the serialisation error. Post it as answer and I'll mark it. – Armin Mar 13 '14 at 15:25
  • Not related, but why you keep calling Super() – Momo Mar 13 '14 at 15:53
  • @Moh that are auto generated constructors in class Parameter, you're right, that's nonsense but it didn't bother me. – Armin Mar 13 '14 at 16:54

1 Answers1

2

Can you change this.valueList = new ArrayList<>(); in SelectParameter to say this.valueList = new ArrayList<String>(); (add the generic type to ArrayList)?

Also, see the "Serializable User-defined Classes" section: http://www.gwtproject.org/doc/latest/DevGuideServerCommunication.html#DevGuideSerializableTypes

3. As of GWT 1.5, it must have a default (zero argument) constructor (with any access modifier) or no constructor at all.

Also make sure #2 applies to your Condition class.

It's also summarized at this Stackoverflow answer: https://stackoverflow.com/a/5210713/1038832

You can also whitelist your custom types for serialization by explicitly mentioning them in a RPC method: https://stackoverflow.com/a/144894/1038832

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