Ant Financial (蚂蚁金服) Java Backend and Middleware Interview Questions

First Round – Ant Financial (蚂蚁金服) Interview

1. Self‑introduction. 2. Differences between ArrayList and LinkedList, ArrayList expansion mechanism and trigger conditions. 3. Implementation of HashMap and its resizing algorithm. 4. Understanding of NIO vs. BIO, and AIO; blocking, non‑blocking, asynchronous I/O details. 5. Concept of distributed services. 6. Tomcat basics: architecture, connector, container. 7. How concurrency is used in projects. 8. Comparison of Docker and virtual machines. 9. Using thread pools under high concurrency. 10. Knowledge of java.util.concurrent, thread‑safe List implementations.

Second Round – Ant Financial (蚂蚁金服) Interview

1. Project overview. 2. Spring source code architecture and workflow. 3. Modifying a Spring bean property during instantiation without constructors or AOP. 4. Tomcat class loader knowledge versus Java class loader. 5. Custom class loader implementation, parent‑delegation model, overriding loadClass and using defineClass. 6. Bloom filter basics, example of IP address filtering. 7. Docker implementation principles: cgroup and namespace isolation. 8. Basic Dubbo architecture and components. 9. Dubbo load‑balancing implementation with code details. 10. Project challenges and personal gains.

Third Round – Ant Financial (蚂蚁金服) Interview

Focus on middleware:

1. Alibaba Dubbo and RocketMQ transactional message architecture. 2. Mycat sharding and partitioning implementation. 3. Message queue technologies such as Kafka and RabbitMQ. 4. Database sharding rules: hash and modulo. 5. Scaling databases from ten‑thousands to hundreds of millions of records. 6. Design ideas for a Double‑11 flash‑sale system.

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