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Best Practices for Synchronizing Threads in Java

Practical suggestions for synchronizing threads in Java include: prioritizing synchronous code blocks over methods; considering ReentrantLock to improve flexibility; avoid deadlocks; and rational use of volatile and atomic classes. 1. When using synchronized keywords, synchronized code blocks are preferred to reduce lock granularity; 2. ReentrantLock provides enhanced functions such as tryLock and timeout mechanism, but locks must be released in finally; 3. Avoid deadlocks can be achieved by unifying the lock order, setting timeouts, reducing the lock range and avoiding nested locks; 4. volatile is suitable for lightweight scenarios that ensure the visibility of variables. Atomic classes such as AtomicInteger can optimize lock-free counting operations.

Jul 09, 2025 am 01:57 AM

Explain the concept of autoboxing and unboxing in Java.

AutoboxingandunboxinginJavaenableautomaticconversionbetweenprimitivesandtheirwrapperclasses.Autoboxingconvertsprimitivestowrapperobjects,suchaswhenaddinganinttoanIntegerlist,whileunboxingextractstheprimitivefromawrapper,likeassigninganIntegertoanint.

Jul 09, 2025 am 01:52 AM

java Automatic packing/unboxing

What are JVM arguments for performance tuning (e.g., -Xms, -Xmx, -XX:)?

ToimproveJavaapplicationperformance,adjustJVMargumentsstartingwithheapsizeusing-Xmsand-Xmxtoavoidmemoryissuesandresizingoverhead,thenchoosetherightgarbagecollectorlikeG1GCforlowlatencyorParallelGCforthroughput,nexttuneGCsettingssuchas-XX:MaxGCPauseMi

Jul 09, 2025 am 01:51 AM

How to handle serialization and deserialization in Java?

Serialization is the process of converting an object into a storageable or transferable format, while deserialization is the process of restoring it to an object. Implementing the Serializable interface in Java can use ObjectOutputStream and ObjectInputStream to operate. 1. The class must implement the Serializable interface; 2. All fields must be serializable or marked as transient; 3. It is recommended to manually define serialVersionUID to avoid version problems; 4. Use transient to exclude sensitive fields; 5. Rewrite readObject/writeObject custom logic; 6. Pay attention to security, performance and compatibility

Jul 09, 2025 am 01:49 AM

java Serialization

What is a Singleton design pattern in Java?

Singleton design pattern in Java ensures that a class has only one instance and provides a global access point through private constructors and static methods, which is suitable for controlling access to shared resources. Implementation methods include: 1. Lazy loading, that is, the instance is created only when the first request is requested, which is suitable for situations where resource consumption is high and not necessarily required; 2. Thread-safe processing, ensuring that only one instance is created in a multi-threaded environment through synchronization methods or double check locking, and reducing performance impact; 3. Hungry loading, which directly initializes the instance during class loading, is suitable for lightweight objects or scenarios that can be initialized in advance; 4. Enumeration implementation, using Java enumeration to naturally support serialization, thread safety and prevent reflective attacks, is a recommended concise and reliable method. Different implementation methods can be selected according to specific needs

Jul 09, 2025 am 01:32 AM

java

What is the main method in Java? (public static void main)

ThemainmethodinJavaistheentrypointofanystandaloneJavaapplication.1.ItmustbedeclaredaspublicsothattheJVMcanaccessit.2.ItmustbestaticsothattheJVMcancallitwithoutcreatinganinstanceoftheclass.3.ItmustreturnvoidbecauseitdoesnotreturnanyvaluetotheJVM.4.Itm

Jul 09, 2025 am 01:30 AM

How to analyze a Java heap dump?

Analyzing Java heap dumps is a key means to troubleshoot memory problems, especially for identifying memory leaks and performance bottlenecks. 1. Use EclipseMAT or VisualVM to open the .hprof file. MAT provides Histogram and DominatorTree views to display the object distribution from different angles; 2. sort in Histogram by number of instances or space occupied to find classes with abnormally large or large size, such as byte[], char[] or business classes; 3. View the reference chain through "ListObjects>withincoming/outgoingreferences" to determine whether it is accidentally held; 4. Use "Pathto

Jul 09, 2025 am 01:25 AM

java

How to implement a caching strategy in Java (e.g., using EhCache or Caffeine)?

ToimproveperformanceinJavaapplications,choosebetweenEhCacheandCaffeinebasedonyourneeds.1.Forlightweight,modernin-memorycaching,useCaffeine—setitupbyaddingthedependency,configuringacachebeanwithsizeandexpiration,andinjectingitintoservices.2.Foradvance

Jul 09, 2025 am 01:17 AM

java caching strategy

Find the first non-repeated character in a string in Java.

The first non-repeat character can be achieved in three ways. Method 1: Use HashMap to count the character frequency and traverse the string twice to find the first character with 1 occurrences, which is suitable for conventional scenarios; Method 2: Use LinkedHashMap to maintain the insertion order, and traverse the key-value pair to return the first character with 1 count. Although the string traversal is reduced, there are still two traversals; Method 3: Use array to count the frequency (limited ASCII characters), which has better performance and is suitable for long strings and limited character sets.

Jul 09, 2025 am 01:05 AM

Java String vs StringBuilder vs StringBuffer

String is immutable, StringBuilder is mutable and non-thread-safe, StringBuffer is mutable and thread-safe. 1. Once the content of String is created cannot be modified, it is suitable for a small amount of splicing; 2. StringBuilder is suitable for frequent splicing of single threads, and has high performance; 3. StringBuffer is suitable for multi-threaded shared scenarios, but has a slightly lower performance; 4. Reasonably set the initial capacity and avoid using String splicing in loops can improve performance.

Jul 09, 2025 am 01:02 AM

java string

What is CompletableFuture in Java?

CompleteFuture is a class introduced by Java 8 to simplify asynchronous programming and multithreaded task processing. 1. It supports manual completion of Future, chain calls, combination of multiple asynchronous operations and unified exception handling; 2. Compared with Java5 Future, it is more powerful, and can manually set results, chain operations, combine tasks and flexibly handle exceptions; 3. Use supplyAsync or runAsync to create asynchronous tasks and specify thread pools; 4. ThenApply convert results, thenAccept consumption results, thenRun to perform subsequent operations; 5. ThenCompose serial combination tasks, thenCombine parallel merge results

Jul 09, 2025 am 12:58 AM

Understanding the Usage of the 'final' Keyword in Java

In Java, the final keyword is used to express immutability, which can improve code security and maintainability. 1. Once the final variable is assigned, it cannot be changed, the basic type value remains unchanged, the reference type address remains unchanged, but the content is variable; 2. The final method cannot be rewritten by subclasses, which helps protect the core logic; 3. The final class cannot be inherited and is suitable for scenarios where intactness is required; 4. Misunderstandings should be avoided when using it. If final is not abused for optimization, note that final does not mean completely immutable, and reasonable use can enhance the clarity of the code.

Jul 09, 2025 am 12:55 AM

Deep Dive into Java Thread Pool Executors

The core parameters of ThreadPoolExecutor include corePoolSize, maximumPoolSize, keepAliveTime, workQueue and handler, which together determine the behavior of the thread pool. 1.corePoolSize specifies the number of core threads, and will not be recycled even if it is idle (unless allowCoreThreadTimeOut is enabled); 2.maximumPoolSize defines the maximum number of threads and controls the upper limit of the thread pool; 3. keepAliveTime sets the idle timeout time of non-core threads; 4.workQueue determines the queuing strategy of the task, if used

Jul 09, 2025 am 12:44 AM

How to properly clone an object in Java?

CloninginJavarequiresunderstandingshallowvsdeepcopying.1.Thedefaultclone()methodperformsashallowcopy,duplicatingtheobjectbutnotitsreferencedobjects,leadingtosharedreferences.2.Fordeepcopying,manuallyclonenestedobjectsbyoverridingclone()inallrelatedcl

Jul 09, 2025 am 12:41 AM