Interview Questions for Java engineers [social recruitment], java engineers

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Author: User
Tags singleton class in java csrf attack

Interview Questions for Java engineers [social recruitment], java engineers


1. What are the features of object orientation?
2. What are the differences between access modifiers public, private, and protected?
3. Is String the most basic data type?
4. Is float f = 3.4 correct?
5. Is there any error in short s1 = 1; s1 = s1 + 1? Short s1 = 1; s1 + = 1; is there a mistake?
6. Is there a goto in Java?
7. What is the difference between int and Integer?
8. What is the difference between & amp; and & amp?
9. Explain the usage of stack, heap, and static area in the memory.
10. What is the value of Math. round (11.5? What is Math. round (-11.5) equal?
11. Can the switch function on byte, long, and String?
12. Calculate 2x8 in the most efficient way?
13. Does the array have the length () method? Does String have the length () method?
14. In Java, how does one jump out of the current multi-nested loop?
15. Can constructor be overwritten )?
16. The two objects have the same value (x. equals (y) = true), but different hash codes are available, right?
17. Can I inherit the String class?
18. when an object is passed as a parameter to a method, this method can change the attributes of this object and return the changed result, so is it a value transfer or a reference transfer?
19. What are the differences between String, StringBuilder, and StringBuffer?
20. Differences between Overload and Override. Can overload methods be differentiated based on the return type?
21. How does JVM load class files?
22. A Chinese character cannot be stored in char variables. Why?
23. What are the similarities and differences between abstract class and interface?
24. What are the differences between Static Nested Class and Inner Class?
25. Is there any memory leakage in Java? Please briefly describe it.
26. can abstract (abstract) methods be both static, local (native), and synchronized?
27. Differences between static variables and instance variables.
28. Can I call non-static (non-static) methods from inside a static (static) method?
29. How to clone objects?
31. String s = new String ("xyz"); how many String objects are created?
32. CAN interfaces inherit (extends) interfaces? Can an abstract class implement the (implements) interface? Can an abstract class inherit a specific class (concrete class )?
33. Can a ". java" source file contain multiple classes (not internal classes )? What are the restrictions?
34. Can Anonymous Inner Class (Anonymous internal Class) inherit other classes? Can I implement interfaces?
35. Can an internal class reference its members that contain classes (external classes? Are there any restrictions?
36. What are the usage of the final keyword in Java?
38. Conversion between data types:
39. How to reverse and replace strings?
40. How to convert a GB2312 encoded string to a ISO-8859-1 encoded string?
41. Date and Time:
42. Print the current time of yesterday.
43. Compare Java and javasrt RT.
44. When can I use assert )?
45. What is the difference between Error and Exception?
46. If there is a return statement in try {}, will the code in finally {} following this try be executed? When will it be executed, before or after return?
47. How to handle exceptions in Java, and how to use keywords: throws, throw, try, catch, and finally?
48. What are the similarities and differences between runtime exceptions and checked exceptions?
49. list some common runtime exceptions?
50. Explain the differences between final, finally, and finalize.
51. Class ExampleA inherits Exception, and class ExampleB inherits ExampleA.
What is the output of the code?
52. Does List, Set, and Map inherit from the Collection interface?
53. describes the storage performance and features of ArrayList, Vector, and sorted list.
54. What is the difference between Collection and Collections?
55. What are the features of access elements using the List, Map, and Set interfaces?
56. How do I compare elements in the sorting of TreeMap and TreeSet? How does the sort () method in the Collections tool class compare elements?
57. What is the difference between the sleep () method of the Thread class and the wait () method of the object that can suspend the Thread execution?
58. What is the difference between the thread sleep () method and the yield () method?
59. After A thread enters the synchronized Method A of an object, can other threads access the synchronized Method B of this object?
60. Describe the methods related to thread synchronization and thread scheduling.
61. How many implementation methods can be used to write multi-threaded programs?
62. How to Use the synchronized keyword?
63. Examples: synchronous and asynchronous.
64. Do I call the run () or start () method to start a thread?
65. What is a thread pool )?
66. What is the relationship between the basic state of the thread and the state?
67. What are the similarities and differences between synchronized and java. util. concurrent. locks. Lock?
68. What is the significance of serialization in Java?
69. How many types of streams are there in Java?
70. Write a method, enter a file name and a string, and count the number of times this string appears in this file.
71. How to Use Java code to list all files in a directory?
72. Use Java socket programming to implement a multi-threaded echo server.
73. How many forms are defined in XML documents? What are the essential differences between them? How can I Parse XML documents?
74. Where do you use XML in your project?
75. Describe the steps for operating the database with JDBC.
76. What is the difference between Statement and PreparedStatement? Which one has better performance?
77. How can I improve the performance of reading data when using JDBC to operate databases? How to improve data update performance?
78. What is the role of the Connection Pool in database programming?
79. What is DAO mode?
80. What is ACID in the transaction?
81. How does one process transactions in JDBC?
82. Can JDBC process Blob and Clob?
83. Briefly describe the regular expression and its usage.
84. How does Java support regular expression operations?
85. How do I obtain a class object?
86. How to create an object through reflection?
87. How can I obtain and set the private field value of an object through reflection?
88. How to call the object through reflection?
89. I would like to briefly describe the "six principles and one law" of object-oriented technology ".
90. Briefly describe the design patterns you know.
91. Write a singleton class in Java.
92. What is UML?
93. What charts are commonly used in UML?
94. Write a bubble sort in Java.
95. Write a half lookup in Java.

Complete Java interview questions (the following lists the questions. For the answers, go to: Full Java interview questions (in ))

96. What are the differences between Servlet and CGI?
97. What methods does the Servlet interface provide?
98. What is the difference between forward and redirect?
99. What built-in objects does JSP have? What are their roles?
100 what are the differences between get and post requests?
101. What are common Web servers?
102. What is the relationship between JSP and Servlet?
103. Explain the four scopes in JSP.
104. How to implement the single-thread mode of JSP or Servlet?
105. What technologies are used to implement session tracking?
106. What are the functions and usage of filters?
107 what are the functions and usage of listeners?
108 what content can be configured in the web. xml file?
109. Which JSTL labels have you used in your project?
110. What are the advantages of using the tag library? How to customize JSP labels?
111. Let's talk about the implicit objects of Expression Language (EL) and their functions.
112 What operators does Expression Language (EL) support?
113 what are Model 1 and Model 2 in Java Web development respectively?
114. What does asynchronous processing in Servlet 3 mean?
115. How to upload and download files in Java-based Web projects?
116 when the server receives the form data submitted by the user, is it calling the Servlet doGet () or doPost () method?
117 what is the difference between static and dynamic content in JSP?
118. How can I obtain user-submitted query parameters or form data in Servlet?
119. How can I obtain the user-configured initialization parameters and server context parameters in Servlet?
120. How do I set the Request Encoding and response content type?
121. Explain the network application mode and its characteristics.
122 what is Web Service )?
123 conceptual explanation: SOAP, WSDL, and UDDI.
124 what are the Java specifications related to Web Services?
125. Introduce the Web Service framework in Java.

126. What is ORM?
127 what are the issues to consider in the design of the persistent layer? What are the persistent layer frameworks you have used?
128. Is SessionFactory thread-safe in Hibernate? Is the Session thread safe? (can two threads share the same Session )?
129 what is the difference between the load and get methods of sessions in Hibernate?
130 What are the functions of the save (), update (), merge (), lock (), saveOrUpdate (), and persist () Methods of the Session? What is the difference?
131 describe the process of loading object by Session.
132 what is the difference between the list method and the iterate method of the Query interface?
133. How does Hibernate implement paging query?
134. What is the use of the lock mechanism? Briefly describe the pessimistic lock and optimistic lock mechanism of Hibernate.
135 describe the three states of object and the conversion relationship.
136. How to understand the delayed Loading Mechanism of Hibernate? In practical applications, how does one deal with the conflict between delayed loading and Session shutdown?
137. Give an example of multi-to-Multi-join and explain how to implement multi-to-Multi-join ing.
138. Let's talk about your understanding of inheritance ing.
139 briefly describe the common optimization strategies of Hibernate.
140 talk about Hibernate's Level 1 cache, level 2 cache, and query cache.
141 what is the DetachedCriteria class in Hibernate?
142. What is the role of the mappedBy attribute of @ onetoworkflow annotation?
143. What is the difference between using <code >#</code> and <code >$ </code> to write placeholders in MyBatis?
144. Explain the role of namespace in MyBatis.
145 what does dynamic SQL in MyBatis mean?
146 what are IoC and DI? How is DI implemented?
147. What are Bean scopes in Spring?
148. What is AOP )?
149. How do you understand the concept of "cross-cutting attention?
150. How do you understand Joinpoint, Pointcut, Advice, Introduction, Weaving, and Aspect in AOP) these concepts?
151. What are the automatic assembly methods in Spring?
152. How to Use annotations in Spring to configure beans? What are the related annotations?
153. What transaction management types does Spring support? Which method do you use in the project?
154. how to configure the Spring IoC container in a Web project?
155. how to configure Spring MVC in a Web project?
156. How does Spring MVC work?
157. how to configure the data source in the Spring IoC container?
158. How do I configure transaction enhancement?
159. Why do I choose to use the Spring framework? (which of the following benefits does Spring framework bring to enterprise-level development )?
160. How does the Spring IoC container configure beans?
161 describe the Bean lifecycle in the Spring framework?
162. How to inject set attributes during dependency injection?
163. What are the restrictions on automatic assembly in Spring?
164. How to obtain the Spring IoC container in a Web project?
165. What problems should large websites consider in terms of architecture?
166. What technologies have you used for browser optimization?
167. What application server optimization technologies have you used?
168. What is XSS attack? What is SQL injection attacks? What is a CSRF attack?
169. What is a domain model )? What is the difference between the anaemic domain model and the rich domain model?
170. Let's talk about the benefits of test-driven development (TDD) and your understanding.

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