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Java > Open Source Codes > com > db4odoc > f1 > queries > NQExample


1 package com.db4odoc.f1.queries;
2
3 import java.util.List JavaDoc;
4
5 import com.db4o.Db4o;
6 import com.db4o.ObjectContainer;
7 import com.db4o.ObjectSet;
8 import com.db4o.query.Predicate;
9 import com.db4o.query.Query;
10
11 public class NQExample {
12     public final static String JavaDoc YAPFILENAME="formula1.yap";
13     
14     public static void main(String JavaDoc[] args) {
15         ObjectContainer db=Db4o.openFile(YAPFILENAME);
16         try {
17             storePilots(db);
18             retrieveComplexSODA(db);
19             retrieveComplexNQ(db);
20             retrieveArbitraryCodeNQ(db);
21             clearDatabase(db);
22         }
23         finally {
24             db.close();
25         }
26     }
27     // end main
28
29     public static void primitiveQuery(ObjectContainer db){
30         List JavaDoc <Pilot> pilots = db.query(new Predicate<Pilot>() {
31             public boolean match(Pilot pilot) {
32                 return pilot.getPoints() == 100;
33             }
34         });
35     }
36     // end primitiveQuery
37
38     
39     public static void advancedQuery(ObjectContainer db){
40         List JavaDoc <Pilot> result = db.query(new Predicate<Pilot>() {
41             public boolean match(Pilot pilot) {
42                 return pilot.getPoints() > 99
43                     && pilot.getPoints() < 199
44                     || pilot.getName().equals("Rubens Barrichello");
45            }
46         });
47     }
48     // end advancedQuery
49
50     public static void storePilots(ObjectContainer db) {
51         db.set(new Pilot("Michael Schumacher",100));
52         db.set(new Pilot("Rubens Barrichello",99));
53     }
54     // end storePilots
55
56     public static void retrieveComplexSODA(ObjectContainer db) {
57         Query query=db.query();
58         query.constrain(Pilot.class);
59         Query pointQuery=query.descend("points");
60         query.descend("name").constrain("Rubens Barrichello")
61             .or(pointQuery.constrain(new Integer JavaDoc(99)).greater()
62                 .and(pointQuery.constrain(new Integer JavaDoc(199)).smaller()));
63         ObjectSet result=query.execute();
64         listResult(result);
65     }
66     // end retrieveComplexSODA
67
68     public static void retrieveComplexNQ(ObjectContainer db) {
69         ObjectSet result=db.query(new Predicate<Pilot>() {
70             public boolean match(Pilot pilot) {
71                 return pilot.getPoints()>99
72                     && pilot.getPoints()<199
73                     || pilot.getName().equals("Rubens Barrichello");
74             }
75         });
76         listResult(result);
77     }
78     // end retrieveComplexNQ
79
80     public static void retrieveArbitraryCodeNQ(ObjectContainer db) {
81         final int[] points={1,100};
82         ObjectSet result=db.query(new Predicate<Pilot>() {
83             public boolean match(Pilot pilot) {
84                 for(int i=0;i<points.length;i++) {
85                     if(pilot.getPoints()==points[i]) {
86                         return true;
87                     }
88                 }
89                 return pilot.getName().startsWith("Rubens");
90             }
91         });
92         listResult(result);
93     }
94     // end retrieveArbitraryCodeNQ
95
96     public static void clearDatabase(ObjectContainer db) {
97         ObjectSet result=db.get(Pilot.class);
98         while(result.hasNext()) {
99             db.delete(result.next());
100         }
101     }
102     // end clearDatabase
103
104     public static void listResult(ObjectSet result) {
105         System.out.println(result.size());
106         while(result.hasNext()) {
107             System.out.println(result.next());
108         }
109     }
110     // end listResult
111 }
112
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