@SerialVersionUID(42L) class Person(val name: String) extends Serializable { private val Friends = new ArrayBuffer[Person]() def addFriend(p: Person) { Friends += p } def isFriend(p: Person) = { Friends.contains(p) } } val paul = new Person("paul") val pierre = new Person("pierre") val jacques = new Person("jacques") paul.addFriend(pierre) pierre.addFriend(paul) jacques.addFriend(paul) jacques.addFriend(pierre) val persons = Array(paul, pierre, jacques) val out = new ObjectOutputStream(new FileOutputStream("c:/ObjectTest.obj")) out.writeObject(persons) out.close val in = new ObjectInputStream(new FileInputStream("c:/ObjectTest.obj")) val Array(paulA, pierreA, jacquesA) = in.readObject().asInstanceOf[Array[Person]] println(jacquesA.isFriend(paulA))