How to resolve java.lang.ClassCastException: hibernate

Question

I have been class it has 5 fields and all are of type String in database(MySQL) the table corresponding to bean has 2 varchar type remaining 3 are integer type. I am performing simple insert operation through session.save(obj) . My Mapping file is as follow ,

<hibernate-mapping>
<class name="com.aurodisplay.its.beans.VehicleRegisterBean"
    table="vehicle_details">
    <id column="vehicleno" name="vehicleno" type="java.lang.Integer">
        <generator class="native" />
    </id>
    <property column="vehicletype" name="vehicletype" type="java.lang.String"></property>
    <property column="model" name="model" type="java.lang.String"></property>
    <property column="clientid" name="clientid" type="java.lang.Integer"></property>
    <property column="groupid" name="groupid" type="java.lang.Integer"></property>

</class>
</hibernate-mapping> 

Here is my Java code snap

Configuration configuration = new Configuration().configure();

    // 2. create sessionfactory
    SessionFactory sessionFactory = configuration.buildSessionFactory();

    // 3. Get Session object
    Session session = sessionFactory.openSession();

    // 4. Starting Transaction
    Transaction transaction = session.beginTransaction();

    VehicleRegisterBean vehicleRegisterBean=new VehicleRegisterBean();


    vehicleRegisterBean.setVehicletype(request.getParameter("vehicletype"));    
    vehicleRegisterBean.setModel(request.getParameter("model"));
    vehicleRegisterBean.setVehicleno(request.getParameter("vehicleno"));

    vehicleRegisterBean.setClientid(request.getParameter("clientid"));
    vehicleRegisterBean.setGroupname(request.getParameter("groupname"));

     session.save(vehicleRegisterBean);
     transaction.commit();
     System.out.println("\n\n Details Added \n");

I am getting ClassCastException,

SEVERE: Servlet.service() for servlet [com.abc.its.controller.VehicleRegister] in context with path [/ITS_Server] threw exception
java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
at org.hibernate.type.IntegerType.set(IntegerType.java:41)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:83)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:60)
at   org.hibernate.persister.entity.AbstractEntityPersister.dehydrate(AbstractEntityPersister.java:1947)
at org.hibernate.persister.entity.AbstractEntityPersister.dehydrate(AbstractEntityPersister.java:1924)
at org.hibernate.persister.entity.AbstractEntityPersister$1.bindValues(AbstractEntityPersister.java:2102)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:32)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2108)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2588)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:48)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)

I am new to hibernate, So can anyone help me to solve this .

Answer 1

change the code to something like this. Debug the code properly, and see which property actually is coming as instance of java.lang.String , ideally the root cause is it should come as Integer only.

But the workaround can be to parse it using

Integer.valueOf(String s);


vehicleRegisterBean.setVehicletype(request.getParameter("vehicletype"));    
vehicleRegisterBean.setModel(request.getParameter("model"));


vehicleRegisterBean.setVehicleno(Integer.valueOf(request.getParameter("vehicleno")));

vehicleRegisterBean.setClientid(Integer.valueOf(request.getParameter("clientid")));
vehicleRegisterBean.setGroupname(Integer.valueOf(request.getParameter("groupname")));

Well, the API for Integer.valueOf(String) does indeed say that the String is interpreted exactly as if it were given to Integer.parseInt(String) . However, valueOf(String) returns a new Integer() object whereas parseInt(String) returns a primitive int.

Now, if what you want is the object and not the primitive, then using valueOf(String)

The database returned no natively generated identity value

I think it means you're trying to use the k generator with a table column which is not properly configured. It should be an auto_increment column for the IDENTITY generator to work. Else, the database doesn't return any generated ID.

Better user type = long

<id column="vehicleno" name="vehicleno" type="java.lang.Integer">
         <generator class="increment"/>
    </id>

Answer 2

Problem lies in these two lines:

vehicleRegisterBean.setClientid(request.getParameter("clientid"));
vehicleRegisterBean.setGroupname(request.getParameter("groupname"));

You are trying to cast String returned from request.getParameter to Integer values.

You need to convert the string values to Integer.

vehicleRegisterBean.setClientid(Integer.valueOf(request.getParameter("clientid")));
vehicleRegisterBean.setGroupname(Integer.valueOf(request.getParameter("groupname")));

Note: You may need to use variables to get the values from request and put in the null checks before converting to Integer.