01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o;
22:
23: import java.util.*;
24:
25: import com.db4o.ext.*;
26:
27: /**
28: * query resultset.
29: * <br><br>An ObjectSet is a representation for a set of objects returned
30: * by a query.
31: * <br><br>ObjectSet extends the system collection interfaces
32: * java.util.List/System.Collections.IList where they are available. It is
33: * recommended, never to reference ObjectSet directly in code but to use
34: * List / IList instead.
35: * <br><br>Note that the underlying
36: * {@link ObjectContainer ObjectContainer} of an ObjectSet
37: * needs to remain open as long as an ObjectSet is used. This is necessary
38: * for lazy instantiation. The objects in an ObjectSet are only instantiated
39: * when they are actually being used by the application.
40: * @see ExtObjectSet for extended functionality.
41: *
42: * @sharpen.extends System.Collections.IList
43: */
44: public interface ObjectSet<Item> extends List<Item>, Iterator<Item> {
45:
46: /**
47: * returns an ObjectSet with extended functionality.
48: * <br><br>Every ObjectSet that db4o provides can be casted to
49: * an ExtObjectSet. This method is supplied for your convenience
50: * to work without a cast.
51: * <br><br>The ObjectSet functionality is split to two interfaces
52: * to allow newcomers to focus on the essential methods.
53: */
54: public ExtObjectSet ext();
55:
56: /**
57: * returns <code>true</code> if the <code>ObjectSet</code> has more elements.
58: *
59: * @return boolean - <code>true</code> if the <code>ObjectSet</code> has more
60: * elements.
61: */
62: public boolean hasNext();
63:
64: /**
65: * returns the next object in the <code>ObjectSet</code>.
66: * <br><br>
67: * Before returning the Object, next() triggers automatic activation of the
68: * Object with the respective
69: * {@link com.db4o.config.Configuration#activationDepth global} or
70: * {@link com.db4o.config.ObjectClass#maximumActivationDepth class specific}
71: * setting.<br><br>
72: * @return the next object in the <code>ObjectSet</code>.
73: */
74: public Item next();
75:
76: /**
77: * resets the <code>ObjectSet</code> cursor before the first element.
78: * <br><br>A subsequent call to <code>next()</code> will return the first element.
79: */
80: public void reset();
81:
82: /**
83: * returns the number of elements in the <code>ObjectSet</code>.
84: * @return the number of elements in the <code>ObjectSet</code>.
85: */
86: public int size();
87: }
|