ExtObjectContainer#isStored helps you to define if the object is stored in the database. The following example shows how to use it:
01private static void checkStored() { 02
// create a linked list with length 10 03
SensorPanel list = new SensorPanel().createList(10); 04
new File(DB4O_FILE_NAME).delete(); 05
ObjectContainer container = Db4o.openFile(DB4O_FILE_NAME); 06
try { 07
// store all elements with one statement, since all 08
// elements are new 09
container.set(list); 10
Object sensor = (Object) list.sensor; 11
SensorPanel sp5 = list.next.next.next.next; 12
System.out.println("Root element " + list + " isStored: " 13
+ container.ext().isStored(list)); 14
System.out.println("Simple type " + sensor 15
+ " isStored: " 16
+ container.ext().isStored(sensor)); 17
System.out.println("Descend element " + sp5 18
+ " isStored: " + container.ext().isStored(sp5)); 19
container.delete(list); 20
System.out.println("Root element " + list + " isStored: " 21
+ container.ext().isStored(list)); 22
} finally { 23
container.close(); 24
} 25
}