title: Add more object into an existing list in hibernate one to many unidirection
body: <p>I have looked into several example on hibernate one-to-many unidirectonal relation, and wonder that how can I add a new object into an existing list.</p>
  
  <p>Assume that I have a class MyClass</p>
  
  <pre><code>@OneToMany(fetch=FetchType.LAZY, cascade={
                      CascadeType.PERSIST, 
                      CascadeType.REMOVE})
  @org.hibernate.annotations.Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
  @JoinTable(name="enrolled_student", 
          joinColumns = {@JoinColumn(name="Class_ID")},
          inverseJoinColumns = {@JoinColumn(name="STUDENT_ID") })
  public List&lt;Student&gt; getStudentList() { return studentList;}
  public void setStudentList(List&lt;Student&gt; studentList) { this.studentList = studentList;}
  private List&lt;Student&gt; List;
  </code></pre>
  
  <p>If I have a list of students such as s1, s2, s3. And now I want to to add student s4 into the class. How can I do that?</p>
  
  <p>I have tried to do as:</p>
  
  <pre><code>@Override
  @Transactional
  public void addStudentToClass(MyClass class, Student student) {
      List&lt;student&gt; list = new ArrayList&lt;Student&gt;();
      list.add(student);
      budget.setStudentList(list);
      classDao.update(budget);
  }
  </code></pre>
  
  <p>But it doesnt work as I expected. It erased all the existing student s1, s2, s3, then persist s4. </p>