java.lang.IllegalArgumentException argument type mismatch

[Mahesh Chandran]

Hi all,

I am trying out Hibernate after longtime. Facing issues right away. I was following some example on the net.

There are three tables: students, courses and student_courses.

Hibernate mappings:
1. Course.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
    <class name="net.sf.hibernate.examples.mysqldbex.Course" table="courses">
        <id name="courseId" column="course_id" type="int" >
            <generator class="increment"/>
        </id>
        
        <property name="courseName" column="course_name"/>
        <property name="description"/>
        <set name="students" table="student_courses"  inverse="true">
            <key column="course_id"/>
            <many-to-many column="student_id" class="net.sf.hibernate.examples.mysqldbex.Student"/>
        </set>
    </class>

</hibernate-mapping>

2. Student.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
    <class name="net.sf.hibernate.examples.mysqldbex.Student" table="students">
        <id name="studentId" column="student_id">
            <generator class="increment"/>
        </id>
                
        <property name="firstName" column="first_name"/>
        <property name="lastName" column="last_name"/>
        <property name="address"/>
        <set name="courses" table="student_courses">
            <key column="student_id"/>
            <many-to-many column="course_id" class="net.sf.hibernate.examples.mysqldbex.Course"/>
        </set>
    </class>

</hibernate-mapping>

Then I have the two POJO classes for Course and Student.

I am trying to execute this code:

        Session sess = null;

        try {
        sess = HibernateUtil.currentSession();
        Transaction tx= sess.beginTransaction();

        Course course = new Course();
        //course.setCourseId(1);
        course.setCourseName("MATHS");
        course.setDescription("MATHEMATICS COURSE");
        out.println("course.desc" + course.getDescription());

        //set students_course SET HERE

        Student stud1 = new Student();
        stud1.setFirstName("AAA");
        stud1.setLastName("BBB");
        stud1.setStudentId(1);
        stud1.setAddress("AAA DRIVE");

        //set students_course SET HERE

        Student stud2 = new Student();
        stud2.setFirstName("AAA1");
        stud2.setLastName("BBB1");
        stud2.setStudentId(2);
        stud2.setAddress("AAA DRIVE1");

        Set<Student> studSet = new HashSet<Student>();
        studSet.add(stud1);
        studSet.add(stud2);

        course.setStudents(studSet);
        out.println("before the save...");
        sess.save(course);
        out.println("saved...");

        tx.commit();
        HibernateUtil.closeSession();
        } catch(Exception e) {
            e.printStackTrace();
        }

Right away I get the error:

net.sf.hibernate.PropertyAccessException: IllegalArgumentException occurred while calling setter of net.sf.hibernate.examples.mysqldbex.Course.courseId
        at net.sf.hibernate.util.ReflectHelper$Setter.set(ReflectHelper.java:71)
        at net.sf.hibernate.persister.AbstractEntityPersister.setIdentifier(AbstractEntityPersister.java:251)
        at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:674)
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:605)
        at org.apache.jsp.index_jsp._jspService(index_jsp.java:127)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
        at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.IllegalArgumentException: argument type mismatch
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at net.sf.hibernate.util.ReflectHelper$Setter.set(ReflectHelper.java:45)
        ... 22 more

I have declared courseId as int in the POJO and in the mapping as you see.

Can you explain why this error happens still?

Thanks,
Mahesh