1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*
* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.stream.Stream;
/**
* The code sample illustrates changes in the reflection API linked
* <b>default methods</b>. Since Java SE 8, a new method is added into the class
* <b><code>java.lang.reflect.Method</code></b>, with which you can reflectively
* determine whether or not a default method provided by an interface
* (<b><code>Method.isDefault()</code></b>).
*/
public class Reflection {
/**
* Base interface to illustrate the new reflection API.
*
* @see Dog
*/
public interface Animal {
/**
* Return string representation of the eat action for Animal
*
* @return string representation of the eat action for Animal
*/
default String eat() {
return this.getClass().getSimpleName()
+ " eats like an ordinary animal";
}
/**
* Return string representation of the sleep action for Animal
*
* @return string representation of the sleep action for Animal
*/
default String sleep() {
return this.getClass().getSimpleName()
+ " sleeps like an ordinary animal";
}
/**
* Return string representation of the go action for Animal
*
* @return string representation of the go action for Animal
*/
String go();
}
/**
* Dog class to illustrate the new reflection API. You can see that:
* <ul>
* <li> the {@link #go} and {@link #sleep} methods are not default.
* {@link #go} is not the default implementation and the {@link #sleep}
* method implementation wins as subtype (according with {@link Inheritance}
* rule. 2) </li>
* <li> the {@link #eat} is a simple default method that is not overridden
* in this class.
* </li>
* </ul>
*/
public static class Dog implements Animal {
/**
* Return string representation of the go action for Dog
*
* @return string representation of the go action for Dog
*/
@Override
public String go() {
return "Dog walks on four legs";
}
/**
* Return string representation of the sleep action for Dog
*
* @return string representation of the sleep action for Dog
*/
@Override
public String sleep() {
return "Dog sleeps";
}
}
/**
* Illustrate the usage of the method java.lang.reflect.Method.isDefault()
*
* @param args command-line arguments
* @throws NoSuchMethodException internal demo error
*/
public static void main(final String[] args) throws NoSuchMethodException {
Dog dog = new Dog();
Stream.of(Dog.class.getMethod("eat"), Dog.class.getMethod("go"), Dog.class.getMethod("sleep"))
.forEach((m) -> {
System.out.println("Method name: " + m.getName());
System.out.println(" isDefault: " + m.isDefault());
System.out.print(" invoke: ");
try {
m.invoke(dog);
} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException ex) {
}
System.out.println();
});
}
}
|
