facing problem while trying to access db

[anish reddy]

java.lang.NoSuchMethodError: java.io.StringWriter.append(Ljava/lang/CharSequence;)Ljava/io/StringWriter;
at javax.persistence.Persistence.createErrorMessage(Persistence.java:258)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:120)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
at org.an.StudentInst.main(StudentInst.java:14)
Exception in thread "main"