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Java > Open Source Codes > com > db4odoc > f1 > evaluations > EvaluationExample


1 package com.db4odoc.f1.evaluations;
2
3 import java.io.*;
4
5 import com.db4o.*;
6 import com.db4o.query.*;
7 import com.db4odoc.f1.*;
8
9
10 public class EvaluationExample extends Util {
11   public static void main(String JavaDoc[] args) {
12     new File(Util.YAPFILENAME).delete();
13     ObjectContainer db=Db4o.openFile(Util.YAPFILENAME);
14     try {
15       storeCars(db);
16       queryWithEvaluation(db);
17     }
18     finally {
19       db.close();
20     }
21   }
22   // end main
23
24   public static void storeCars(ObjectContainer db) {
25     Pilot pilot1=new Pilot("Michael Schumacher",100);
26     Car car1=new Car("Ferrari");
27     car1.setPilot(pilot1);
28     car1.snapshot();
29     db.set(car1);
30     Pilot pilot2=new Pilot("Rubens Barrichello",99);
31     Car car2=new Car("BMW");
32     car2.setPilot(pilot2);
33     car2.snapshot();
34     car2.snapshot();
35     db.set(car2);
36   }
37   // end storeCars
38
39   public static void queryWithEvaluation(ObjectContainer db) {
40     Query query=db.query();
41     query.constrain(Car.class);
42     query.constrain(new EvenHistoryEvaluation());
43     ObjectSet result=query.execute();
44     listResult(result);
45   }
46   // end queryWithEvaluation
47
48   public static void listResult(ObjectSet result) {
49       System.out.println(result.size());
50       while(result.hasNext()) {
51           System.out.println(result.next());
52       }
53   }
54   // end listResult
55 }
56
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