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Java — вопросы для собеседования
288+ вопросов для подготовки к собеседованию по Java
130 Junior
97 Middle
61 Senior
1
What is Java and what is it used for?
junior
2
What is the JVM (Java Virtual Machine)?
junior
3
What is the difference between JDK, JRE, and JVM?
junior
4
What is the difference between == and .equals() in Java?
junior
5
What is the difference between abstract class and interface in Java?
middle
6
What is the difference between String, StringBuilder, and StringBuffer in Java?
junior
7
What is the difference between ArrayList and LinkedList in Java?
junior
8
What is the difference between HashMap and HashTable in Java?
junior
9
What is the difference between checked and unchecked exceptions in Java?
middle
10
What is the difference between final, finally, and finalize in Java?
junior
11
What is the difference between == and equals()?
junior
12
What is the difference between abstract class and interface?
junior
13
What is the difference between String, StringBuilder, and StringBuffer?
junior
14
What is the difference between ArrayList and LinkedList?
junior
15
What is the difference between HashMap and HashTable?
junior
16
What is the difference between checked and unchecked exceptions?
junior
17
What is the difference between final, finally, and finalize?
junior
18
What is the difference between == and equals()?
junior
19
What is the difference between abstract class and interface?
junior
20
What is the difference between String, StringBuilder, and StringBuffer?
junior
21
What is the difference between ArrayList and LinkedList?
junior
22
What is the difference between HashMap and HashTable?
junior
23
What is the difference between checked and unchecked exceptions?
junior
24
What is the difference between final, finally, and finalize?
junior
25
What is the difference between == and equals()?
junior
26
What is the difference between abstract class and interface?
junior
27
What is the difference between String, StringBuilder, and StringBuffer?
junior
28
What is the difference between ArrayList and LinkedList?
junior
29
What is the difference between HashMap and HashTable?
junior
30
What is the difference between checked and unchecked exceptions?
junior
31
What is the difference between final, finally, and finalize?
junior
32
What is the difference between == and equals()?
junior
33
What is the difference between abstract class and interface?
junior
34
What is the difference between String, StringBuilder, and StringBuffer?
junior
35
What is the difference between ArrayList and LinkedList?
junior
36
What is the difference between HashMap and HashTable?
junior
37
What is the difference between checked and unchecked exceptions?
junior
38
What is the difference between final, finally, and finalize?
junior
39
What is the difference between == and equals()?
junior
40
What is the difference between abstract class and interface?
junior
41
What is the difference between String, StringBuilder, and StringBuffer?
junior
42
What is the difference between ArrayList and LinkedList?
junior
43
What is the difference between HashMap and HashTable?
junior
44
What is the difference between checked and unchecked exceptions?
junior
45
What is the difference between final, finally, and finalize?
junior
46
What is the difference between == and equals()?
junior
47
What is the difference between abstract class and interface?
junior
48
What is the difference between String, StringBuilder, and StringBuffer?
junior
49
What is the difference between ArrayList and LinkedList?
junior
50
What is the difference between HashMap and HashTable?
junior
51
What is the difference between checked and unchecked exceptions?
junior
52
What is the difference between final, finally, and finalize?
junior
53
What is the difference between == and equals()?
junior
54
What is the difference between abstract class and interface?
junior
55
What is the difference between String, StringBuilder, and StringBuffer?
junior
56
What is the difference between ArrayList and LinkedList?
junior
57
What is the difference between HashMap and HashTable?
junior
58
What is the difference between checked and unchecked exceptions?
junior
59
What is the difference between final, finally, and finalize?
junior
60
What is the difference between == and equals()?
junior
61
What is the difference between abstract class and interface?
junior
62
What is the difference between String, StringBuilder, and StringBuffer?
junior
63
What is the difference between ArrayList and LinkedList?
junior
64
What is the difference between HashMap and HashTable?
junior
65
What is the difference between checked and unchecked exceptions?
junior
66
What is the difference between final, finally, and finalize?
junior
67
What is the difference between == and equals()?
junior
68
What is the difference between abstract class and interface?
junior
69
What is the difference between String, StringBuilder, and StringBuffer?
junior
70
What is the difference between ArrayList and LinkedList?
junior
71
What is the difference between HashMap and HashTable?
junior
72
What is the difference between checked and unchecked exceptions?
junior
73
What is the difference between final, finally, and finalize?
junior
74
What is the difference between == and equals()?
junior
75
What is the difference between abstract class and interface?
junior
76
What is the difference between String, StringBuilder, and StringBuffer?
junior
77
What is the difference between ArrayList and LinkedList?
junior
78
What is the difference between HashMap and HashTable?
junior
79
What is the difference between checked and unchecked exceptions?
junior
80
What is the difference between final, finally, and finalize?
junior
81
What is the difference between == and equals()?
junior
82
What is the difference between abstract class and interface?
junior
83
What is the difference between String, StringBuilder, and StringBuffer?
junior
84
What is the difference between ArrayList and LinkedList?
junior
85
What is the difference between HashMap and HashTable?
junior
86
What is the difference between checked and unchecked exceptions?
junior
87
What is the difference between final, finally, and finalize?
junior
88
What is the difference between == and equals()?
junior
89
What is the difference between abstract class and interface?
junior
90
What is the difference between String, StringBuilder, and StringBuffer?
junior
91
What is the difference between ArrayList and LinkedList?
junior
92
What is the difference between HashMap and HashTable?
junior
93
What is the difference between checked and unchecked exceptions?
junior
94
What is the difference between final, finally, and finalize?
junior
95
What is the difference between == and equals()?
junior
96
What is the difference between abstract class and interface?
junior
97
What is the difference between String, StringBuilder, and StringBuffer?
junior
98
What is the difference between ArrayList and LinkedList?
junior
99
What is the difference between HashMap and HashTable?
junior
100
What is the difference between checked and unchecked exceptions?
junior
101
Jackson: JSON serialization/deserialization?
middle
102
JUnit 5: advanced features?
middle
103
Spring Boot: Graceful Shutdown?
senior
104
Spring Boot: environment profiling for production and development?
junior
105
Spring Boot: HTTP Caching?
middle
106
Spring Boot: WebSocket with STOMP?
middle
107
Spring Boot and MongoDB?
middle
108
Spring Boot and Redis: sessions and caching?
middle
109
Spring Boot and Apache Kafka?
senior
110
Spring Boot: Scheduled Tasks?
junior
111
Spring Boot and Elasticsearch?
middle
112
Spring Boot: validation and @Valid?
middle
113
Spring Boot and GraphQL?
senior
114
Reactive Programming: WebFlux vs MVC?
senior
115
Proxy Pattern in Spring?
senior
116
Spring Boot and API documentation generation (OpenAPI)?
junior
117
Spring Boot and JUnit 5: integration tests?
middle
118
Spring Boot and Observability (Metrics, Tracing, Logging)?
senior
119
Spring Boot 3: most important changes?
senior
120
What is the difference between Comparable and Comparator in Java?
middle
121
What is the difference between throw and throws in Java?
junior
122
What is the difference between final, finally, and finalize?
junior
123
What is the difference between == and equals()?
junior
124
What is the difference between abstract class and interface?
junior
125
What is the difference between String, StringBuilder, and StringBuffer?
junior
126
What is the difference between ArrayList and LinkedList?
junior
127
What is the difference between HashMap and HashTable?
junior
128
What is the difference between checked and unchecked exceptions?
junior
129
What is the difference between final, finally, and finalize?
junior
130
What is the difference between == and equals()?
junior
131
What is the difference between abstract class and interface?
junior
132
What is the difference between String, StringBuilder, and StringBuffer?
junior
133
What is the difference between ArrayList and LinkedList?
junior
134
What is the difference between HashMap and HashTable?
junior
135
What is the difference between checked and unchecked exceptions?
junior
136
What is the difference between final, finally, and finalize?
junior
137
What is the difference between == and equals()?
junior
138
What is the difference between abstract class and interface?
junior
139
What is the difference between String, StringBuilder, and StringBuffer?
junior
140
What is the difference between ArrayList and LinkedList?
junior
141
What is the difference between HashMap and HashTable?
junior
142
What is the difference between checked and unchecked exceptions?
junior
143
What is the difference between final, finally, and finalize?
junior
144
What is the difference between == and equals()?
junior
145
What is the difference between abstract class and interface?
junior
146
What is the difference between String, StringBuilder, and StringBuffer?
junior
147
What is the difference between ArrayList and LinkedList?
junior
148
What is the difference between HashMap and HashTable?
junior
149
What is the difference between checked and unchecked exceptions?
junior
150
What is the Stream API in Java and what is it used for?
middle
151
What are intermediate and terminal operations in Streams?
middle
152
What is the difference between map() and flatMap() in Streams?
middle
153
What are Collectors in Java Streams?
middle
154
What is the reduce() operation in Streams?
middle
155
What is a parallel stream in Java?
middle
156
What are functional interfaces in Java?
middle
157
What are lambda expressions in Java?
middle
158
What is Optional in Java and how to use it?
middle
159
What is the difference between Stream.collect() and Stream.reduce()?
middle
160
What is the difference between map() and mapToInt/mapToDouble?
middle
161
What is the difference between Stream.findFirst() and findAny()?
middle
162
What is the difference between Stream.anyMatch() and Stream.allMatch()?
middle
163
What is the difference between Stream.count() and Collection.size()?
middle
164
What is the difference between Stream.skip() and Stream.limit()?
middle
165
What is the difference between Stream.distinct() and Collection.stream().filter()?
middle
166
What is the difference between Stream.peek() and Stream.map()?
middle
167
What is the difference between Stream.sorted() and Collections.sort()?
middle
168
What is the difference between Stream.toArray() and List.toArray()?
middle
169
What is the difference between Stream.flatMap() and Stream.map()?
middle
170
What is the difference between Stream.collect(Collectors.toList()) and Stream.toList()?
middle
171
What is the difference between Stream.map() and Stream.collect()?
middle
172
What is the difference between Stream.filter() and Stream.takeWhile()?
middle
173
What is the difference between Stream.dropWhile() and Stream.skip()?
middle
174
What is the difference between Stream.anyMatch() and Stream.noneMatch()?
middle
175
What is the difference between Stream.collect() and Stream.reduce()?
middle
176
What is the difference between Stream.findFirst() and Stream.findAny()?
middle
177
What is the difference between Stream.map() and Stream.flatMap()?
middle
178
What is the difference between Stream.min() and Stream.max()?
middle
179
What is the difference between Stream.forEach() and Stream.collect()?
middle
180
What is the difference between Stream.limit() and Stream.takeWhile()?
middle
181
What is the difference between Stream.skip() and Stream.dropWhile()?
middle
182
What is the difference between Stream.allMatch() and Stream.noneMatch()?
middle
183
What is the difference between Stream.distinct() and Stream.filter()?
middle
184
What is the difference between Stream.peek() and Stream.forEach()?
middle
185
What is the difference between Stream.sorted() and Stream.map()?
middle
186
What is the difference between Stream.count() and Stream.reduce()?
middle
187
What is the difference between Stream.collect() and Stream.toArray()?
middle
188
What is the difference between Stream.findFirst() and Stream.min()?
middle
189
What is the difference between Stream.findAny() and Stream.max()?
middle
190
What are Records in Java and why were they introduced?
middle
191
What is the difference between Records and Classes in Java?
middle
192
What is a compact canonical constructor in Records?
middle
193
What are static fields and methods in Records?
middle
194
What is the difference between Record and Lombok @Data?
middle
195
What is the difference between Record and Class for DTOs?
middle
196
What are Virtual Threads in Java?
senior
197
What is the difference between Virtual Threads and Platform Threads?
senior
198
What is Structured Concurrency in Java?
senior
199
What is Scoped Values in Java?
senior
200
What is Spring Boot?
middle
201
What is the difference between @SpringBootApplication and @Configuration?
middle
202
What is the difference between @Component, @Service, and @Repository?
middle
203
What is the difference between @Autowired and constructor injection?
middle
204
What is the difference between @Value and @ConfigurationProperties?
middle
205
What is the difference between @RestController and @Controller?
middle
206
What is the difference between @RequestMapping and @GetMapping?
middle
207
What is the difference between @RequestBody and @RequestParam?
middle
208
What is the difference between @PathVariable and @RequestParam?
middle
209
What is the difference between @RequestParam and @ModelAttribute?
middle
210
What is the difference between @Valid and @Validated?
middle
211
What is the difference between @SpringBootApplication and @EnableAutoConfiguration?
middle
212
What is the difference between @Bean and @Component?
middle
213
What is JPA (Java Persistence API)?
middle
214
What is the difference between JPA and Hibernate?
middle
215
What is the difference between @Entity and @Table?
middle
216
What is the difference between @Id and @GeneratedValue?
middle
217
What is the difference between @Column and @JoinColumn?
middle
218
What is the difference between @OneToMany and @ManyToOne?
middle
219
What is the difference between @OneToOne and @ManyToOne?
middle
220
What is the difference between @ManyToMany and @OneToMany?
middle
221
What is the difference between FetchType.LAZY and FetchType.EAGER?
middle
222
What is the difference between CascadeType.ALL and cascade = {CascadeType.PERSIST, CascadeType.MERGE}?
middle
223
What is the difference between JPA Repository and CrudRepository?
middle
224
What is the difference between JPQL and SQL?
middle
225
What is the difference between @Query and @Modifying?
middle
226
What is the difference between @Transactional and @Version?
middle
227
What is the difference between @PersistenceContext and @Autowired?
middle
228
What is the difference between findById() and getReferenceById()?
middle
229
What is the difference between save() and saveAndFlush()?
middle
230
What is Microservices architecture?
senior
231
What is the difference between Monolith and Microservices?
senior
232
What is Service Discovery?
senior
233
What is API Gateway?
senior
234
What is Circuit Breaker pattern?
senior
235
What is the difference between synchronous and asynchronous communication?
senior
236
What is the difference between REST and gRPC?
senior
237
What is Event-Driven Architecture?
senior
238
What is the difference between Kafka and RabbitMQ?
senior
239
What is Distributed Tracing?
senior
240
What is the difference between Centralized and Decentralized Configuration?
senior
241
What is the difference between Load Balancing client-side and server-side?
senior
242
What is the difference between Idempotent and Non-Idempotent operations?
senior
243
What is the difference between SAGA and Two-Phase Commit?
senior
244
What is the difference between CQRS and Traditional CRUD?
senior
245
What is Event Sourcing?
senior
246
What is the difference between Horizontal and Vertical Scaling?
senior
247
What is the difference between Availability and Consistency?
senior
248
What is the JVM Memory Model?
senior
249
What is the difference between Heap and Stack?
senior
250
What is Garbage Collection in Java?
senior
251
What is the difference between G1 and ZGC?
senior
252
What is JIT Compiler?
senior
253
What is the difference between Class Loading and Linking?
senior
254
What is ClassLoader in Java?
senior
255
What is the difference between Minor and Major GC?
senior
256
What is the difference between Soft, Weak, and Phantom References?
senior
257
What is the difference between Serial GC and Parallel GC?
senior
258
What is the difference between Stop-the-World and Concurrent GC?
senior
259
What is the difference between Metaspace and PermGen?
senior
260
What is the difference between Young Generation and Old Generation?
senior
261
What is the difference between Eden and Survivor spaces?
senior
262
What is the difference between CMS and G1 GC?
senior
263
What is the difference between Thread and Virtual Thread?
senior
264
What is the difference between wait() and sleep()?
senior
265
What is the difference between synchronized and volatile?
senior
266
What is the difference between ConcurrentHashMap and Hashtable?
senior
267
What is the difference between fail-fast and fail-safe iterators?
senior
268
What is the difference between HashMap and LinkedHashMap?
senior
269
What is the difference between WeakHashMap and IdentityHashMap?
senior
270
What is a sealed class in Java 17?
middle
271
What are records in Java 16+?
middle
272
What is pattern matching for switch in Java 21?
senior
273
What are virtual threads in Java 21?
senior
274
What is the difference between Spring Boot and Spring Framework?
middle
275
What is Spring Bean lifecycle?
senior
276
What is Spring AOP?
senior
277
What is the difference between @Autowired and @Resource?
middle
278
What is Spring Data JPA?
middle
279
What is the difference between @Transactional and programmatic transactions?
senior
280
What is Spring Security?
senior
281
What is the difference between ConcurrentHashMap and Collections.synchronizedMap?
senior
282
What is CompletableFuture in Java?
senior
283
What is the Stream API in Java?
middle
284
What is the Optional class in Java?
middle
285
What is the difference between REST and GraphQL?
senior
286
What is the Flyway migration tool?
middle
287
What is the Liquibase migration tool?
middle
288
What is the difference between ExecutorService and ForkJoinPool?
senior
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