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lMingyul

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Futu Interview Experience - First Round

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This post is translated from Chinese into English through AI.View Original
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The interview experience was good, with the interviewer providing guidance throughout. However, the interviewee struggled with outdated knowledge. The interview covered topics such as Java basics, concurrency, JVM, databases, data structures and algorithms, and projects. Some specific questions included the differences between String, StringBuilder, and StringBuffer, the usage and differences between ArrayList and LinkedList, the usage and issues with HashMap in concurrent scenarios, the reasons for using a thread pool instead of creating new threads, the usage of synchronized keyword and its effects, the differences between Sleep() and Wait() methods, GC models in Java virtual machine, transaction levels and examples in MySQL, different types of locks in MySQL, the efficiency of primary key index compared to regular index, introduction to quicksort and heapsort, and writing recursive methods for inorder and preorder traversal of a binary tree. In the project section, the interviewee was asked to explain their previous projects, the reasons for using SpringCloud's OpenFegin for calling third-party services, the implementation of log calling chain in the project, the differences between MySQL and ProgresSQL, and the process of smoothly switching databases without stopping the service. Lastly, a scenario was presented where a user successfully receives the result of step A but the service crashes before step B (asynchronous logging) is completed, and the interviewee was asked how they would handle the lost log in this situation.

The experience of the interview was good, the interviewer has been guiding, but it has been a long time since I have dealt with standardized writing 🤣

  • Position: Backend Development
  • Date: 2023-05
  • Interview Duration: 1 hour 24 minutes

Java#

Basics#

  • What is the difference between String, StringBuilder, and StringBuffer?

    • What is the reason for the better performance of StringBuilder?

  • What are the List implementations used in Java development? Can you explain their characteristics?

    • What is the difference between ArrayList and LinkedList?

  • What are the Map implementations used in Java development? Can you explain their characteristics?

    • What problems can occur with HashMap in concurrent scenarios, and what methods can be used to solve them?

Concurrency#

  • In daily development, when do you need to use a thread pool?

    • Why do we use a thread pool instead of directly creating a new thread?

  • Besides using multithreading, what other approaches do you use to solve concurrency problems in programming (such as locks)?

    • Have you used the synchronized keyword in Java? Can you explain how it is generally used?
    • Can synchronized be used to modify methods? What phenomenon will occur?

  • What is the usage and difference between Sleep() and Wait() methods?

JVM Virtual Machine#

  • Are you familiar with Java Virtual Machine's garbage collection (GC)?
    • Which GC model is used in your project?

Database#

  • What are the transaction isolation levels in MySQL? Can you give an example for each level?
  • Can you introduce MySQL locks, such as gap locks?
  • Are you familiar with indexes?
    • Why is the query efficiency of primary key indexes faster than that of regular indexes?
    • What is the difference between unique indexes and primary key indexes?

Data Structures and Algorithms#

  • Please introduce quicksort and heapsort.
  • Write the inorder and preorder traversal of a binary tree using recursion.

Projects#

  • Please provide a detailed explanation of the projects you have worked on.
  • Why did you use SpringCloud's OpenFeign to call third-party services in your project?
  • How is the log calling chain implemented in your project, and how does it work in practice?
  • What are the differences between MySQL and ProgresSQL, and why did you switch the database from MySQL to ProgresSQL?
  • How do you achieve a smooth transition during the database switching migration process?
    • How do you achieve a smooth database switch without stopping the service?
  • Scenario: Calling an API where Step A is executed sequentially and Step B is executed asynchronously in the background to record the call log (which takes longer to execute). Now, if Step A is successful and returned to the user, but the service crashes during the execution of Step B and the log is not recorded, how would you handle this situation?
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