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[jdom-interest] NPE on Serialization

Jan Kriesten

2007-07-10

Replies:


Hi,

I get the following NPE on serializing JDOM 1.0:

---8<---
11:17:15.220 ERROR [org.apache.wicket.util.lang.Objects       ] - Error
serializing object class de.silberlicht.wsl.test.HelloWor
ld [object=[Page class = de.silberlicht.wsl.test.HelloWorld, id = 3, version = 0]]
java.lang.NullPointerException
    at org.jdom.filter.ElementFilter.writeObject (ElementFilter.java:167)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
---8<---

In ElementFilter.java:167 there's no check whether or not 'namespace' is
actually set.

Changing writeObject() to

---8<---
  private void writeObject(ObjectOutputStream out) throws IOException {

    out.defaultWriteObject();

    // We use writeObject() and not writeUTF() to minimize space
    // This allows for writing pointers to already written strings
    if( namespace!=null )
    {
      out.writeObject(namespace.getPrefix());
      out.writeObject(namespace.getURI());
    }
  }
---8<---

solves the problem. Does this have any side-effects?

Best regards, --- Jan.

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