MersenneTwisterRNG serialization

[Alfonso Garcia]

Is the MersenneTwisterRNG class really serializable? The following test fails and I can't quite understand why, as all declared members appear to be Serializable

import org.uncommons.maths.random.MersenneTwisterRNG;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;

public class MersenneSerializationTest {

    @Test
    public void testMersenneSerialization() throws IOException {

        Random r = new MersenneTwisterRNG();
       
        FileOutputStream fos = new FileOutputStream("data/engine_mersennetest.ser");
        DebugObjectOuputStream oos = new ObjectOuputStream(fos);
       
        oos.writeObject(r);
       
        oos.close();
        fos.close();

    }

}

The stack trace says

java.io.NotSerializableException: java.lang.Object
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347)
    at MersenneSerializationTest.testMersenneSerialization