试题如下：
参考答案：
|
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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
import java.io.FileNotFoundException;import java.io.IOException;import java.util.ArrayList;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * Created by ysc on 7/26/16. */public class Interview { private static void one(){ String str1 = "hello"; String str2 = "he"+new String("llo"); System.err.println(str1==str2); System.out.println("1. false"); } private static void two(){ int i = Integer.MAX_VALUE; System.err.println((i+1)<i); System.out.println("2. 存在一个i, 使得(i+1)<i"); } private static void three(){ System.err.println("gc is not a Java Thread, it is a native thread"); Thread.getAllStackTraces().keySet().forEach(thread -> System.out.println(thread.getName()+"->"+thread.isDaemon()+" "+thread.getPriority())); System.out.println("3. gc线程是daemon线程"); } private static volatile int count = 0; private static void four(){ ExecutorService executorService = Executors.newCachedThreadPool(); for(int j=0; j<10; j++){ executorService.submit(()->{ for(int i=0; i<1000000; i++){ count++; } }); } System.out.println("count should be: "+10000000+", actual be: "+count); System.out.println("4. volatile不能保证线程安全"); } private static void five(){ ArrayList<Integer> list = new ArrayList<>(20); list.add(1); System.out.println("debug code, not execute grow method"); System.out.println("5. list grow 0 times"); } private static void six() { System.out.println("BufferedReader's constructor only accepts a Reader instance"); System.out.println("6. new BufferedReader(new FileInputStream(\"a.dat\")); is wrong"); } private static void seven() { try{ if(true){ throw new IOException(); } }catch (FileNotFoundException e){ System.out.print("FileNotFoundException!"); }catch (IOException e){ System.out.print("IOException!"); }catch (Exception e){ System.out.print("Exception!"); } System.out.println("\n7. IOException!"); } private static void eight() { System.out.println("String s;System.out.println(s); error: variable s might not have been initialized\nRecompile with -Xlint:unchecked for details."); System.out.println("8. 由于String s没有初始化, 代码不能编译通过"); } private static void nine() { System.out.println("5"+2); System.out.println("9. 52"); } private static void ten() { int i = 2; int result = 0; switch(i){ case 1: result = result + i; case 2: result = result + i * 2; case 3: result = result + i * 3; } System.out.println("result="+result); System.out.println("10. 10"); } private static class Null{ public static void hello(){ System.out.println("hello"); } public static void main(String[] args) { ((Null)null).hello(); Null _null = (Null)null; _null.hello(); } } private static class StringExample1{ String str = new String("good"); char[] ch = {'a', 'b', 'c'}; public void change(String str, char[] ch){ str = "test ok"; ch[0] = 'g'; } public static void main(String[] args) { StringExample1 ex = new StringExample1(); ex.change(ex.str, ex.ch); System.out.print(ex.str+" and "); System.out.print(ex.ch); System.out.println(); } } private static class StringExample2{ public static void change(String str){ str = "welcome"; } public static void main(String[] args) { String str = "1234"; change(str); System.out.println(str); } } private static class ForLoop{ static boolean foo(char c){ System.out.print(c); return true; } public static void main(String[] args) { int i=0; for(foo('A');foo('B')&&(i<2);foo('C')){ i++; foo('D'); } System.out.println(); } } private static class HelloA{ public HelloA(){ System.out.println("HelloA"); } { System.out.println("I'm A class"); } static { System.out.println("static A"); } } private static class HelloB extends HelloA{ public HelloB(){ System.out.println("HelloB"); } { System.out.println("I'm B class"); } static { System.out.println("static B"); } public static void main(String[] args) { System.out.println("main start"); new HelloB(); new HelloB(); System.out.println("main end"); } } public static void main(String[] args) { one(); two(); three(); four(); five(); six(); seven(); eight(); nine(); ten(); Null.main(null); StringExample1.main(null); StringExample2.main(null); ForLoop.main(null); HelloB.main(null); }} |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
