Java serialization raises utfdataformatexception

Question

I am trying to serialize multiple objects to a file. In particular, when I try to write

public void execute(PipelineContext context) throws Exception { FileOutputStream fos = new FileOutputStream("test_audit_trail2.objects"); ObjectOutputStream oos = new ObjectOutputStream(fos); BigInteger rho = (BigInteger) context.get("rho"); BigInteger p = (BigInteger) context.get("p"); BigInteger xS = (BigInteger) context.get("xs"); BigInteger zSBar = (BigInteger)context.get("zsbar"); int nS = (Integer) context.get("ns"); P2PShuffler ownShuff = (P2PShuffler) context.get("shuffler"); HexCryptor cryptor = (HexCryptor) context.get("cryptor"); String[] PRPrimePrimeBar = (String []) context.get("pr_prime_prime_bar"); P2PAuditTrailGenerator ownATG = (P2PAuditTrailGenerator) context.get("p2p_audit_trail_generator"); int kS = (Integer) context.get("ks"); oos.writeObject(rho); oos.writeObject(p); oos.writeObject(xS); oos.writeObject(zSBar); oos.writeObject(ownShuff); oos.writeObject(cryptor); oos.writeObject(PRPrimePrimeBar); oos.writeObject(ownATG); oos.writeObject(nS); oos.writeObject(kS); 

This happens fine, all writeObject succeeds, and I definitely close the corresponding threads. However, when I try to recover all objects by calling readObject (), I encounter a UTFDataFormatException

 java.io.UTFDataFormatException at java.io.ObjectInputStream$BlockDataInputStream.readUTFSpan(ObjectInputStream.java:3081) at java.io.ObjectInputStream$BlockDataInputStream.readUTFBody(ObjectInputStream.java:3006) at java.io.ObjectInputStream$BlockDataInputStream.readUTF(ObjectInputStream.java:2819) at java.io.ObjectInputStream.readUTF(ObjectInputStream.java:1050) at java.io.ObjectStreamClass.readNonProxy(ObjectStreamClass.java:614) at java.io.ObjectInputStream.readClassDescriptor(ObjectInputStream.java:808) at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1564) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1495) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1315) at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1911) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1873) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350) at edu.foo.peer.pipeline.AuditTrailCheckStageTest.setUp 

After commenting on readObject and writeObject one by one it seems that leaving P2PAuditTrailGenerator out of this allows me to read all objects successfully. Looking at this class, it seems that there are no String related objects.

 public class P2PAuditTrailGenerator implements Serializable { private int num; private BigInteger phi; private BigInteger rho; /** * @param auditTrailSecretKeys The secret keys used for audit trail */ private BigInteger[] auditTrailSecretKeys; private BigInteger[] encAuditTrails; private Random rnd; public BigInteger [] getAuditTrailSecretKeys(){ return auditTrailSecretKeys; } public P2PAuditTrailGenerator(int num, BigInteger rho, BigInteger phi) { this.num = num; this.phi = phi; this.rho = rho; auditTrailSecretKeys = new BigInteger[num]; encAuditTrails = new BigInteger[num]; rnd = new Random(); } public BigInteger[] generateATs() { for (int i = 0; i < num; i++) { //assuming the security parameter is always 512 or 1024; auditTrailSecretKeys[i] = new BigInteger(200, rnd).mod(phi); encAuditTrails[i] = rho.modPow(auditTrailSecretKeys[i], phi); } return encAuditTrails; } } 

Identifying the wrong class, and if not, what happened to my implementation?

Answer 1

I assume that you declared P2PAuditTrailGenerator serializable, but it does not have a constructor with no arguments. Everything else looks fine.