JPA question (Scala using) - database

Question

OpenJPA and Scala question.
There are 2 tables in database (h2) - tasks and taskLists.
TaskList contains collection ArrayList.
Each TaskList can contain tasks from another TaskLists
When taskX modified in TaskList1 it have to be modified in TaskList2, if it contains taskX.
How to implement this?
I can add new task to task list and save it to DB, but when I try to add taskX from TaskList1 tasks collection to TaskList2 tasks collection and persist it, taskX is not persisted in db.
Example:
1. Adding task1 to taskList1 and task2 to taskList2 will result:
TaskList1: [task1]
TaskList2: [task2]
2. Adding task2 to taskList1 will result:
TaskList1: [task1]
3. Adding task3 to taskList1 and task4 to taskList2 will result:
TaskList1: [task1, task3]
TaskList2: [task2, task4]
What is wrong?
Task class:
import _root_.javax.persistence._
import org.apache.openjpa.persistence._
#Entity
#Table(name="tasks")
#ManyToMany
class CTask (name: String) {
def this() = this("new task")
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(unique = true, nullable = false)
var id: Int = _
var title: String = name
def getId = id
def getTitle = title
def setTitle(titleToBeSet: String) = title = titleToBeSet
override def toString: String = title
}
TaskList class:
import _root_.javax.persistence._
import _root_.java.util.ArrayList
import org.apache.openjpa.persistence._
#Entity
#Table(name="tasklists")
class CTaskList(titleText: String) {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(unique = true, nullable = false)
var id: Int = _
#Column(nullable = false)
var title: String = titleText
#ManyToMany
var tasks: ArrayList[CTask] = _;
var tags: String = ""
var rank: Int = 0
def getTasks = tasks
def this() = this("new task list")
def createTasks: ArrayList[CTask] = {
tasks = new ArrayList[CTask]
tasks
}
def getID = id
def getTags = tags
def setTags(tagsParam: String) = tags = tagsParam
def getRank = rank
def setRank(rankParam: Int) = rank = rankParam
def getTitle: String = title
def getTaskById(index: Int): CTask = {
null
}
def equals(anotherTaskList: CTaskList): Boolean = {
if (anotherTaskList == null) return false
if (anotherTaskList.getTasks == null)
return id == anotherTaskList.getID && title == anotherTaskList.getTitle && tags == anotherTaskList.getTags && rank == anotherTaskList.getRank && tasks == null;
else
return id == anotherTaskList.getID && title == anotherTaskList.getTitle && tags == anotherTaskList.getTags && rank == anotherTaskList.getRank && tasks != null && tasks.size == anotherTaskList.getTasks.size
}
def addTask(taskToBeAdded: CTask): Int = {
if (tasks == null)
tasks = new ArrayList[CTask]
tasks.add(taskToBeAdded)
tasks.indexOf(taskToBeAdded)}
def printTasks = println("TaskList's " + this + " tasks: " + tasks)
}

Answer 1

As far as I know, Many-To-Many association (as specified in your mapping annotations) implies association table between two entities (i.e. #JoinTable annotation should be specified).