Alibaba Java Post interview experience __java

First of all, Ali's interviewers are very nice, each end of the phone will say thank you, asked you will not be a problem, will make you do not worry, will give you tips, interview experience is very good.

The first time, 10 o'clock in the morning the phone to the bathroom, did not receive, a little side.

3 o'clock in the afternoon, Ali telephone side, should be a technology brother, chatting with me a lot of mess, in the middle I may be a little nervous, speak a bit fast, little brother let me not hurry, said my knowledge is very wide, do not be afraid. Then I was very calm and nice to chat with little brother.

Little brother came up to ask the project experience, here skip. Then asked two simple algorithms, the array in reverse order (direct two pointers to one end of the exchange, and the stack, first in and then out, and then I said the stack is not good, occupy a large space, the second is to find an array of K the largest number, I said to build a K-group of small top heap, and then found that larger than the minimum, on the update heap, the complexity of ( NLOGK).

Then little brother asked me what courses to learn better, I said cryptography, and then little brother let me explain the principle of SSL, crying, I really do not know, I know he is used to visit the site encryption, and then to the younger brother introduced a bit of rsa,aes. Remember it.

Little brother asked me what to learn good, I said math, small brother Leng, and then talked to me about the algorithm, dynamic planning of the idea, I said is a phased solution, the latter phase dependent on the previous phase of the solution. That's probably it. Maybe a little bit more, and now I'm going to make a comparison with the greedy algorithm and list the different scenarios for the two algorithms. Next time ask me what to learn good, I said the database still has the design pattern, originally how did not think.

Young brother also asked the principles of SPRING,IOC and AOP, have been applied, and implemented (AOP implementations may not be very good, dynamic proxy jdk reflection, and filters)

Then ask me Java garbage collection (some of the places remember some vague, memory is not enough when garbage collection, in fact, is exactly so Eden space to complete the memory allocation, when Eden full, and then create objects.) Because the application is not available, Division Minor GC. (EDEN+S0 or EDEN+S1) generation of garbage collection, Minor GC, Eden space can not be recycled objects into the empty survivor (S0 or S1,eden will certainly be emptied), Another survivor cannot be put into this by a GC, and a survivor must be guaranteed to be empty. Step3 if survivor full, then these objects will be copy to old area, or survivor is not full, but some objects enough to be put into old spaces, when old is full of time, to carry out fully GC.

Ask me about a problem in my project, there is a memory leak, memory leak is a long lived object holding a reference to a short-lived object, resulting in short-lived objects can not be released. There are also some performance optimizations.

Evening 8:00 Ali Two, technical elder brother, direct ask concurrent programming. syntronized internal implementation, I said lock (there are some other things, temporarily not sorted).

Runnable and thread difference, one is the class is an interface, and (did not know) Runnable can facilitate the sharing of resources, thread does not, thread implementation of the Runnable interface

Related Materials Reference http://developer.51cto.com/art/201203/321042.htm

The difference between run () and Statr () I think there is a more detailed and professional answer http://www.cnblogs.com/linjiqin/archive/2011/04/10/2011272.html

Asked the design pattern of a single case pattern and decorator pattern

Asked if the override and overload return values are not the same as overloading

Asked the HashMap's implementation

Two days later Ali three sides:

Introduce yourself

Project experience

Spring

The difference between an abstract class and an interface

Java garbage Collection

Make a list of the books I've read:

The Java programming thought reads carefully

Java core technology sweeps through a few chapters

Data structure and algorithm analysis-java language description fine-read handwritten code implementation

Effective Java read 1/2 Thoughts on Java Common knowledge point is now looking at

Deep understanding of Java Virtual machines focus on memory recycling and class loading

Java concurrent Programming read some chapters are currently looking at

The foundation of algorithm design and analysis

Introduction to algorithms read a few chapters

Programming Zhuji is mainly about programming ideas

A deep understanding of the computer network looked at several chapters tcp-udp HTTP

Big talk design pattern 21 kinds of design patterns some things are not very clear.

The 13 design patterns commonly used in heard first design pattern are explained clearly

Heard first Sevelet &jsp read 1/2 understand some basic things

Programmer Interview Book feeling is three books inside looking at the most pleasing to the eye

The sword refers to the offer many examples use C + + realization to look uncomfortable

The beauty of programming is a lot of fun ideas.