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