国产. 精品,99视频30精品视频在线观看

Article Tags

Home

Technical Articles

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

How to handle exceptions in Java using try-catch-finally?

In Java, the most commonly used way to deal with exceptions is the try-catch-finally structure, which is the core of which is to understand the functions of each part separately and use it reasonably. 1. The try block is used to wrap code that may throw exceptions, and it should avoid containing too much irrelevant logic; 2. The catch block is captured and processed in sequence from subclass to parent class according to the specificity of the exception. It is recommended to record logs or prompt the user to avoid empty catch; 3. The finally block will be executed regardless of whether an exception occurs. It is suitable for closing resources, but be careful that it is executed before return and may not be executed in extreme cases; 4. Using multiple exception merging writing and try-with-resources can improve the simplicity and security of the code; 5. Do not swallow exceptions, at least

Jul 09, 2025 am 12:32 AM

How to implement the Command design pattern in Java?

To implement the command design pattern, you must first clarify its core composition and implement it step by step. 1. Understand the core components of the command mode: including command interface, specific command classes, receivers, callers and clients; 2. Define command interfaces, usually including execute() method; 3. Create recipient classes that perform actual operations such as Light; 4. Implement specific command classes such as LightOnCommand and LightOffCommand to encapsulate receiver methods; 5. Use callers such as RemoteControl to trigger commands; 6. Create and bind commands and receivers on the client, and execute operations through the caller. This mode implements requested encapsulation, operation decoupling and functional expansion.

Jul 09, 2025 am 12:28 AM

java command mode

How to solve java.lang.UnsatisfiedLinkError?

java.lang.UnsatisfiedLinkError is usually caused by the JVM's inability to load the required local library. Solutions include: 1. Ensure that the native library file exists and the path is correct. You can specify the path through -Djava.library.path; 2. Use System.loadLibrary() or System.load() to load the library correctly; 3. Confirm that the library matches the current platform and CPU architecture, and automatically select the appropriate version according to the environment; 4. Check and install other system libraries or third-party libraries that the native library depends on to ensure the dependency is complete.

Jul 09, 2025 am 12:15 AM

What is the difference between fail-fast and fail-safe iterators in Java?

Fail-fastiteratorsthrowConcurrentModificationExceptionwhenstructuralchangesoccurduringiteration,whilefail-safeiteratorsoperateonasnapshotanddonotthrowexceptions.1.Fail-fastdetectsmodificationsviaacounterandthrowsexceptionsunlesschangesaremadethrought

Jul 09, 2025 am 12:09 AM

Practical Examples of Java Lambda Expressions

LambdaexpressionsinJavasimplifycodingbyenablingconciseandreadableimplementations.1.Theystreamlinedatafilteringwithstreams,asseenwhenselectingemployeesbysalarythresholdusingfilter()withalambdacondition.2.Lambdasallowinlineimplementationoffunctionalint

Jul 08, 2025 am 02:55 AM

expression

Understanding Java NIO and Its Advantages

JavaNIO is a new IOAPI introduced by Java 1.4. 1) is aimed at buffers and channels, 2) contains Buffer, Channel and Selector core components, 3) supports non-blocking mode, and 4) handles concurrent connections more efficiently than traditional IO. Its advantages are reflected in: 1) Non-blocking IO reduces thread overhead, 2) Buffer improves data transmission efficiency, 3) Selector realizes multiplexing, and 4) Memory mapping speeds up file reading and writing. Note when using: 1) The flip/clear operation of the Buffer is easy to be confused, 2) Incomplete data needs to be processed manually without blocking, 3) Selector registration must be canceled in time, 4) NIO is not suitable for all scenarios.

Jul 08, 2025 am 02:55 AM

java nio

Java Serialization vs Externalization Differences

Serializable and Externalizable interfaces in Java are used for object serialization, but there are key differences. 1. Serializable is a tag interface that automatically handles serialization, suitable for simple scenarios but lacks control; 2. Externalizable inherits from Serializable, forcing writeExternal and readExternal methods to provide finer granular control, suitable for performance and format sensitive scenarios; 3. Serializable is easy to use but may cause version compatibility issues, and serialVersionUID needs to be explicitly declared; 4. Externalizable needs to be managed manually

Jul 08, 2025 am 02:55 AM