Serialization

[Douglas Ferguson]

Why do Wicket-serialized objects require a default constructor?

Exception is:

Caused by: 
java.io.InvalidClassException:com.conducive.logic.scraper.impl.media.MediaScraperResult;
 com.conducive.logic.scraper.impl.media.MediaScraperResult; no valid 
constructor     
java.io.ObjectStreamClass.checkDeserialize(ObjectStreamClass.java:713)

     java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1733)

     java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)

     java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1945)

     java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1869)

     java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)

     java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)

     java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1945)

     java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1869)

     java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)

     java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)

     java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1945)

     java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:480)

     org.apache.wicket.Component.readObject(Component.java:4228)

     sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

     
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

     
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

     java.lang.reflect.Method.invoke(Method.java:597)

     java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)

     java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1846)

     java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)

     java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)

     java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1945)

     java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:480)

     org.apache.wicket.Component.readObject(Component.java:4228)

     sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

     
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

     
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

     java.lang.reflect.Method.invoke(Method.java:597)

     java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)

     java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1846)