Article Tags
Article Tags
How to Connect to a MySQL Database with Java? (JDBC Basics)
To fill in the parameters correctly, ensure that the URL contains serverTimezone (such as?serverTimezone=UTC&useSSL=false), use the mysql-connector-java driver that matches the JDK version, the account password is valid and not empty, and the connection must be closed with try-with-resources.
Mar 05, 2026 am 12:15 AM
How to use the Arrays tool class to operate arrays in Java_Advanced tips for Java arrays
Arrays.asList() returns an immutable internal class and does not support add/remove; newArrayList() is required to convert it to a mutable collection; Arrays.sort() uses dual-axis quick sort for basic types and Timsort for object arrays; Arrays.equals() compares elements by elements, and deepEquals is required for two-dimensional arrays; Arrays.fill() reference types will share the same instance.
Mar 04, 2026 am 11:03 AM
How to use Java's Timer and TimerTask to implement timers_Simple task scheduling implementation
Why Timer and TimerTask easily miss cancel(), causing memory leaks. Java's Timer is a single-thread scheduler, and all TimerTasks are executed on the same background thread; once the task is not explicitly canceled, the Timer instance will always hold a strong reference to the task, even if the external object is no longer reachable. The JVM will not recycle it, and the background thread continues to run, creating an implicit memory leak. Common error phenomenon: OutOfMemoryError:unabletocreatenewnativethread, especially in web applications that frequently create new Timers (such as every HTTP request
Mar 04, 2026 am 11:00 AM
How to use Java's Stream.iterate to generate an infinite sequence_Advanced usage of streaming programming
The program freezes or OOMs when Stream.iterate generates an infinite sequence. Since there is no termination condition by default, calling collect(), count() and other non-short-circuit operations will generate infinite elements. It must be used in conjunction with limit(), takeWhile() (Java9) or findFirst(), and seed and unaryOperator must be of the same type, pure functions, and avoid object reuse.
Mar 04, 2026 am 10:57 AM
How to write a simple password strength detector in Java_regular and scoring algorithm
How to use String.matches() to determine basic password rules. The most direct regular verification method in Java is String.matches(), but it anchors the entire string by default (equivalent to ^...$), which is easy to misjudge - for example, if you want to check "whether it contains numbers", writing "[0-9]" will fail because the entire string is not matched. Detect "at least one number": use s.matches(".*[0-9].*") or the more reliable Pattern.compile("[0-9]").matcher(s).find() to detect "must contain both uppercase and lowercase letters and numbers"
Mar 04, 2026 am 10:54 AM
How to configure the MyBatis environment in Java development_SqlSessionFactory and configuration file description
The key to not reporting NullPointerException during SqlSessionFactory initialization is to ensure that the configuration file path is correct, the XML format is legal, and is loaded by classpath: mybatis-config.xml must be placed under src/main/resources, the root node is and contains and, the namespace of MapperXML must be strictly consistent with the fully qualified name of the interface, and SqlSessionFactory should be used as a thread-safe global singleton.
Mar 04, 2026 am 10:51 AM
Detailed explanation of cross-core synchronization overhead in Java_Atomic maintenance of MESI protocol in multi-processor environment
Volatile writes cannot avoid cross-core cache synchronization, and they still rely on the MESI protocol to broadcast invalidate requests, causing cache line contention and bus bandwidth saturation.
Mar 04, 2026 am 10:48 AM
CAS atomic operation principle in Java_Optimistic lock implementation and solution strategy to ABA problem
compareAndSet is not equal to absolute thread safety, because it only checks whether the value has changed and ignores the modification process, causing ABA problems; AtomicStampedReference prevents ABA through version numbers, and AtomicMarkableReference is only suitable for binary state switching.
Mar 04, 2026 am 10:45 AM
How to use do-while to implement interactive menu in Java_Java practice project
The do-while loop must be jumped out with break, otherwise it will easily end in an endless loop. Java's do-while is executed first and then judged. The menu logic is naturally suitable for it - the user sees the menu at least once before deciding whether to exit. But novices often write the exit condition at the end of the loop body but forget to add break, or write the while condition as always true (such as while(true)) without adding break, and the result is stuck on the console. The correct approach is: put the exit logic in the loop body, use break to actively jump out, and the while condition is only responsible for full verification. Don't write while(true) and then break by if(choice==0)
Mar 04, 2026 am 10:42 AM
Elementary practice: How to write a simple console blog searcher in Java_String matching
String.contains() is not suitable for blog search because it only supports strict substring matching and cannot handle case, spaces, punctuation, spelling errors, synonyms and fuzzy queries; preprocessing toLowerCase() indexOf() or escaped wildcard regular matching (such as .*java.*config.*) is a more practical lightweight alternative.
Mar 04, 2026 am 10:39 AM
Principles and limitations of using bounded wildcards to instantiate generic classes in Java
This article explains in detail why MyArrayList
Mar 04, 2026 am 10:36 AM
The correct way to send emails in batches using JavaMail API in Java
This article explains in detail how to correctly set multiple recipients (BCC/CC/TO) through javax.mail in Java, solves common misunderstandings - repeatedly calling setRecipients() causes only the first/last address to take effect, and provides a safe and reusable code implementation.
Mar 04, 2026 am 10:33 AM
How to independently manage Boolean status for a Discord server (Guild) (JDA tutorial)
This article explains in detail how to maintain command switch status separately for each server in JDA (JavaDiscordAPI), avoid cross-server status pollution caused by global Boolean variables, and provide memory mapping and persistence expansion solutions.
Mar 04, 2026 am 10:30 AM
Detailed explanation of StringBuilder.reverse in Java_The simplest implementation of string reverse order
StringBuilder.reverse() directly reverses the internal char[] array in place, with time complexity O(n), space O(1), and no new objects are created; it does not process encoding logic and is safe for legal UTF-16 sequences (including emoji proxy pairs), but if the source data is damaged, it will still be invalid after flipping.
Mar 04, 2026 am 10:27 AM
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