BAT Recruitment interview Java Technology 100 problem Summary __java

BAT Recruitment interview Java Technology 100 questions summary

Too many questions, so just do the summary, do not answerAli School Recruit what is the parent class for all classes in 1.java. He has a way of doing it. What design pattern is applied to the InputStream under the IO package in 2.java. Please describe the design pattern you know? the difference between 3.ArrayList and LinkedList is detailed. the difference between 4.session and cookies. 5. Say a quick sort of principle. 6. Brief introduction to AOP and its role. the 7.STRUTS2 process. 8.java Some classes need to implement the serializable interface. the difference between the 9.hashmap,hashtable. And how to use it, as well as some of his methods. 10. Design questions, using HashMap to order the weight of apples. 11.STRUTS2 Interceptor related issues. Struts2 the way in which parameters are accepted. 12. Problems related to anomalies. Error and exception specific. 13.servlet related knowledge, dopost,doget, some built-in objects. the difference between 14.set and list, some implementation classes, inheritance relationships 、、。 15. Database transaction isolation mechanism and what is its characteristics. 16.JVM memory heap and Stack 17.HTTP message contains content. 18. How to calculate the time complexity in data structure, the difference between linked list and array 19. Write out the quick row, and say the time complexity of the fast row, and what is the worst case 20. How floating-point numbers are stored in the computer, 0.1+0.2 why, 0.30000000000000004 21.new What happens to a constructor when an object is returned, and if the active return is an object, what returns? 22. When transmitting data over the network, it is often necessary to convert the binary data to a printable string, and the commonly used printable character set contains 64 characters, so it is also called the Base64 notation, and an existing char array of length 12 is represented as a Base64 string. Would the BASE64 string require at least a few chars, and a few char if the length of char is 20? 23. Suppose that the payment of a treasure envelope password supports a combination of 1 to 6 digits, that is, ' 0′, ' 1′, ' 003 ' and ' 999999 ' are all legal red envelope passwords, so how many legal red envelopes can be given in total. 24. A two-fork tree with 513 nodes, is there a possible layer height of _ species? 25. Given an integer sum, look for element a,b,c,d from an array of n unordered elements, making a + B + c + d = SUM, the fastest average time complexity is _? 26.hashtable,hashmap,concurrenthashmap Bottom implementation principle and thread safety problem (recommend familiar with JDK source code, can answer calmly) What kinds of reference types are 27.Java? 28. The difference between abstract classes and interfaces 29. What are the design patterns 30. Advantages of the Factory method model (low coupling, cohesion well-structured classes, open closure principle) 31. How arrays are accessed in the old age 32.GC algorithm, permanent generation object How GC, GC has loop how to deal with 33. Who will be GC, when GC 34. What if you don't want to be a GC? 35. What if you want to survive 1 times in the GC? 36.hashCode () and Equals () generation algorithm, and methods how to rewrite 37. Sorting algorithm and complexity of space-time 38. Find trees and red and black trees 39.JVM How to allocate direct memory, how the new object is not allocated on the heap but on the stack, constant pool parsing 40.HashMap and thread safety issues 41.JVM The process of how to load a class, and what methods are in the parent delegation model. 42. There are several ways in which interprocess communication is available. in the reference Accessibility analysis algorithm for 43.GC, which objects can be used as GC roots objects. 44.JVM How the GC, the Cenozoic, the old, the persistent generation, all store what things. How to schedule the process under 45.Linux. 46.Linux The commands you use frequently. 47. What are the commonly used hash algorithms? What is a consistent hash. 48. What are the paradigms in the database? What is the Nio,bio,aio in 49.Java? 50. There is now a thread in the JVM that hangs and uses tools to isolate the cause. 51. The relationship between thread synchronization and blocking. Synchronization must be blocked. Blocking must be synchronized. 52. What is the difference between synchronization and asynchrony? 53. How to create a single case pattern. Said a double check, he said it was not thread safe. How to efficiently create a single example of thread safety. 54.concurrent bag below, have used anything. 55. Know which design patterns. Tell me what design patterns have been used. 56. What is the anonymous inner class? How to access a variable that is defined outside it. is the byte limit of 57.get a limitation of the protocol itself ? How does 58.hashtable implement thread safety? Hashtable principle? 59. Database transaction isolation mechanism and characteristics? Database engine? 60.dns is based on TCP or UDP 61. What data structure does the connection pool use use to realize? 62.https How to be safe 63.b+ tree and two fork tree find time complexity 64. When will the JVM heap (persistent zone) memory overflow occur? Memory overflow What should I do? Tencent School Recruit 1. How to optimize the array of this data structure. 2.Mongo features, and the difference between MySQL 3.contains and Comparedocumentposition differences and use 4. Link list judgment loop and find connection point 5. Two stack implementation queue, how to achieve multithreading concurrency 6. Whether the arbitrary merging of two strings can be a third string 7.linux kernel State and user state, why is this so divided. The difference between 8.TCP and UDP, TCP is how to do error handling. 9. What does the system and hard disk do when reading the file? 10.select, poll, and Epoll the difference between forward () and redirect () in the 11.SERVLET API. Baidu School Recruit 1.hashmap and Hashtable difference 2. The understanding of thread safety 3. Talking about the three major architectures of the Web 4. Why use struts to do MVC 5. What technology is about decoupling how the 6.AOP is implemented How the 7.java agent is implemented the difference between 8.http and HTTPS 9.get submission and post submission differences 10. How to solve Chinese garbled problem 11. Design Pattern 12. Your understanding of MVC the difference between 13.XML and JSON. Which traffic is larger for JSON and XML. 14. The difference between abstract classes and interfaces 15. How to quickly identify your current location of the nearest 100 restaurants (cannot be traversed) 16. Code implementation depth first and breadth first 17. Computer network layering, each layer uses the protocol, the Protocol occupies the port 18. A large number of data found every day to visit Baidu site most of the first 100 people's IP address 19. Optimistic Lock pessimistic lock 20. Database index, database paradigm 21.osi seven-layer model and TCP/IP four-tier model 22. Memory overflow and memory leak