Formerly called 'Code to 35'. Add our main WeChat ID to access a wealth of shared resources (algorithms, interview prep, tech stacks: Java, Python, Go, big data). We mainly share serious development techniques, focusing on output-driven input. Occasionally we post life snippets and gossip. Our aim is to attract precise traffic and test advertising opportunities.
This article explains Java's Exchanger class, detailing its synchronization mechanism, internal source‑code structure, practical usage examples, and how it compares with other concurrency utilities such as CyclicBarrier, Semaphore, and SynchronousQueue.
The article explains the requirements and usage of Jackson’s @JsonAnyGetter and @JsonAnySetter annotations, showing how to serialize dynamic properties into JSON and deserialize them back into a Java object, with complete code examples and step‑by‑step demonstrations.
This article presents a MySQL interview case that examines e‑commerce repurchase behavior using orders and users tables, defines repeat purchasers, computes average repurchase intervals and amounts, identifies high‑value customers, and aggregates results by city through CTEs, window functions, and grouped statistics.
The article shows how to use MySQL CTEs and window functions to identify e‑commerce users who spent over 10,000 CNY in 2023, calculate their average spend and order count, determine their share of all users, and break the results down by city.
This article presents an e‑commerce interview case that defines three tables (orders, order_items, products), loads sample data, and walks through a step‑by‑step SQL solution using CTEs, aggregation, window functions and HAVING to calculate each customer's total spend, most expensive order, and favorite product category, filtering and sorting the results.
The article explains Elasticsearch's disk watermark mechanism—low, high, and flood stage thresholds—detailing why they are crucial for preventing data loss and maintaining cluster stability, how they work, how to configure them in elasticsearch.yml, and best‑practice recommendations for monitoring and storage planning.
This article explains Java 8's StampedLock—its optimistic and pessimistic read/write modes, internal state handling, source‑code walkthrough, typical usage scenarios, and a performance comparison with ReentrantLock and ReentrantReadWriteLock—providing concrete code examples and detailed analysis for developers.
This article provides an in‑depth overview of Java’s Collections Framework, detailing the core interfaces (List, Set, Queue, Deque, Map), their major implementations, performance characteristics, thread‑safety considerations, iterator usage, utility classes, and concurrent collection options, illustrated with code examples and diagrams.
This article compiles a concise reference of fifty commonly used Linux commands, detailing each command’s purpose, typical usage syntax, concrete examples, and handy tips to help developers and system administrators quickly master essential command‑line operations.
This article explains how Java’s garbage collector interacts with the four reference types—Strong, Soft, Weak, and Phantom—detailing their behavior, typical use cases, and code examples that show when each reference allows an object to be reclaimed.
