Method: unwrap()

1: /*
2: * JOPA
3: * Copyright (C) 2024 Czech Technical University in Prague
4: *
5: * This library is free software; you can redistribute it and/or
6: * modify it under the terms of the GNU Lesser General Public
7: * License as published by the Free Software Foundation; either
8: * version 3.0 of the License, or (at your option) any later version.
9: *
10: * This library is distributed in the hope that it will be useful,
11: * but WITHOUT ANY WARRANTY; without even the implied warranty of
12: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13: * Lesser General Public License for more details.
14: *
15: * You should have received a copy of the GNU Lesser General Public
16: * License along with this library.
17: */
18: package cz.cvut.kbss.jopa.proxy.lazy;
19:
20: /**
21: * Marker interface for lazy loading proxy implementations.
22: *
23: * @param <T> Type of the loaded value
24: */
25: public interface LazyLoadingProxy<T> {
26:
27: /**
28: * Triggers value loading.
29: *
30: * @return Loaded value
31: */
32: T triggerLazyLoading();
33:
34: /**
35: * Checks whether this proxy has already been loaded.
36: *
37: * @return {@code true} if this proxy has been loaded, {@code false} otherwise
38: */
39: boolean isLoaded();
40:
41: /**
42: * If this proxy has already been loaded, this method returns the loaded value.
43: *
44: * @return The loaded value, {@code null} if this proxy has not been loaded, yet
45: * @see #isLoaded()
46: * @throws IllegalStateException If called before this proxy is loaded
47: */
48: T getLoadedValue();
49:
50: /**
51: * Gets a value that should be used to replace this proxy outside a persistence context.
52: *
53: * @return Default value to replace this proxy with
54: */
55: default T unwrap() {
56: return null;
57: }
58: }