To correctly handle JDBC transactions, you must first turn off the automatic commit mode, then perform multiple operations, and finally commit or rollback according to the results; 1. Call conn.setAutoCommit(false) to start the transaction; 2. Execute multiple SQL operations, such as INSERT and UPDATE; 3. Call conn.commit() if all operations are successful, and call conn.rollback() if an exception occurs to ensure data consistency; at the same time, try-with-resources should be used to manage resources, properly handle exceptions and close connections to avoid connection leakage; in addition, it is recommended to use connection pools and set save points to achieve partial rollback, and keep transactions as short as possible to improve performance.

Pre-formanceTartuptimeMoryusage, Quarkusandmicronautleadduetocompile-Timeprocessingandgraalvsupport, Withquarkusoftenperforminglightbetterine ServerLess scenarios.2.Thyvelopecosyste,

Java's garbage collection (GC) is a mechanism that automatically manages memory, which reduces the risk of memory leakage by reclaiming unreachable objects. 1.GC judges the accessibility of the object from the root object (such as stack variables, active threads, static fields, etc.), and unreachable objects are marked as garbage. 2. Based on the mark-clearing algorithm, mark all reachable objects and clear unmarked objects. 3. Adopt a generational collection strategy: the new generation (Eden, S0, S1) frequently executes MinorGC; the elderly performs less but takes longer to perform MajorGC; Metaspace stores class metadata. 4. JVM provides a variety of GC devices: SerialGC is suitable for small applications; ParallelGC improves throughput; CMS reduces

ExecutorService is suitable for asynchronous execution of independent tasks, such as I/O operations or timing tasks, using thread pool to manage concurrency, submit Runnable or Callable tasks through submit, and obtain results with Future. Pay attention to the risk of unbounded queues and explicitly close the thread pool; 2. The Fork/Join framework is designed for split-and-governance CPU-intensive tasks, based on partitioning and controversy methods and work-stealing algorithms, and realizes recursive splitting of tasks through RecursiveTask or RecursiveAction, which is scheduled and executed by ForkJoinPool. It is suitable for large array summation and sorting scenarios. The split threshold should be set reasonably to avoid overhead; 3. Selection basis: Independent

Gradleisthebetterchoiceformostnewprojectsduetoitssuperiorflexibility,performance,andmoderntoolingsupport.1.Gradle’sGroovy/KotlinDSLismoreconciseandexpressivethanMaven’sverboseXML.2.GradleoutperformsMaveninbuildspeedwithincrementalcompilation,buildcac

The clear answer to this question is the recommendation to implement the observer pattern using a custom observer interface. 1. Although Java provides Observable and Observer, the former is a class and has been deprecated and lacks flexibility; 2. The modern recommended practice is to define a functional Observer interface, and the Subject maintains the Observer list and notify all observers when the state changes; 3. It can be used in combination with Lambda expressions to improve the simplicity and maintainability of the code; 4. For GUI or JavaBean scenarios, PropertyChangeListener can be used. Therefore, new projects should adopt a custom observer interface scheme, which is type-safe, easy to test and specializes in modern Java

The volatile keyword is used to ensure that the read and write of variables occurs directly in main memory. 1. It ensures that variable modifications are immediately visible to all threads, and avoids threads reading expired values due to local cache; 2. It is suitable for scenarios such as flag bit control, double-check lock singletons, and ensures safe release of objects; 3. However, it does not guarantee the atomicity of composite operations. For example, AtomicInteger or synchronized is required for self-increase. Therefore, volatile is suitable for scenarios that require visibility but no atomicity, and cannot replace the synchronization mechanism. Its limitations must be clarified when using it.

Choosing the right HTMLinput type can improve data accuracy, enhance user experience, and improve usability. 1. Select the corresponding input types according to the data type, such as text, email, tel, number and date, which can automatically checksum and adapt to the keyboard; 2. Use HTML5 to add new types such as url, color, range and search, which can provide a more intuitive interaction method; 3. Use placeholder and required attributes to improve the efficiency and accuracy of form filling, but it should be noted that placeholder cannot replace label.