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Java vs. Kotlin: A Detailed Comparison for Android and Backend Development

Kotlin is better than Java in terms of syntax simplicity, and has empty security, data classes, extended functions and intelligent type inference, which significantly improves development efficiency; 2. Kotlin is recommended for Android development, because of Google's official support, JetpackCompose and coroutine integration, and can be interoperated with Java to achieve gradual migration; 3. The Java ecosystem in back-end development is more mature and stable, suitable for large enterprise systems, and Kotlin is more suitable for new microservices with the advantages of deep integration with SpringBoot, coroutine support and functional programming; 4. Java learning resources are rich and the community is huge, suitable for beginners. Although Kotlin has a certain learning threshold, the community is developing rapidly; 5. New Andr

Aug 08, 2025 am 04:49 AM

Check whether the sorted subarray exists in a larger sorted array: O(log n) Time complexity implementation

This article introduces a method to determine whether a sorted subarray of length k exists in a sorted array of length n within the O(max(log n, k)) time complexity. The core idea is to use binary search to locate the starting element of the subarray and then perform linear verification. The article elaborates on the implementation principle of this method in detail and analyzes its time complexity, providing readers with an efficient solution.

Aug 08, 2025 am 04:30 AM

How to create a singleton in Java

Eagerinitializationcreatestheinstanceatclassloading,isthread-safebutnotlazy;2.Lazyinitializationwithdouble-checkedlockingprovidesthreadsafetyandlazyloadingusingvolatileandsynchronized;3.Staticinnerclassmethodisrecommendedforitssimplicity,laziness,and

Aug 08, 2025 am 04:25 AM

java

How to match a pattern with the Pattern class in Java

First, use the Pattern.compile() method to compile the regular expression into a Pattern object; 2. Then call the matcher() method of the object to create a Matcher instance to match the input string; 3. Use the find() method to find all matches or matches() method to verify the exact match; 4. You can extract the matching content through the group() method or use flags such as CASE_INSENSITIVE to ignore case and other matches; 5. For one-time matching, you can directly use the static Pattern.matches() method to complete. This method is suitable for simple verification, and finally select the appropriate method to complete the pattern matching task according to your needs.

Aug 08, 2025 am 03:22 AM

How to make a GET request in Java?

Use HttpURLConnection (built-in in Java, no dependencies): Send GET requests through URL and HttpURLConnection classes, set request methods and header information, read response codes and response bodies, suitable for scenarios without external dependencies, but the code is lengthy and error-prone. 2. Use HttpClient (Java11): A modern HTTP client introduced by Java11 supports smooth syntax and asynchronous requests, configures timeouts and read responses concisely. It is recommended for new projects in Java11 and above. 3. Use ApacheHttpClient (external library): powerful function, suitable for complex scenarios, need to add Maven dependencies, and use Clo

Aug 08, 2025 am 03:01 AM

java get request

How to create a modular application in Java 9

Create a modular application of Java9, you must first write the module-info.java file to define the module name, dependency and export package; 2. Organize the code according to the standard directory structure, such as src/module name/; 3. Use javac to compile to the output directory with --module-source-path and -d; 4. Run the main class of the specified module through java-module-path and -m; 5. If there is a dependency, you must declare requirements in module-info and compile together; 6. You can optionally use the jar command to package it as a modular JAR and run it with --module-path; modularity improves maintainability through clear encapsulation and dependencies, and must be exported to access

Aug 08, 2025 am 02:49 AM

java modularity Java 9

How to parse XML with SAX in Java?

Create a custom DefaultHandler and rewrite startElement, endElement, characters and other methods to handle parse events; 2. Create a SAXParser instance using SAXParserFactory, and associate the XML file with the custom processor through the parse method for parse; 3. SAX parsing is based on event-driven, with low memory usage, and is suitable for large files, but can only be read in sequence and cannot modify XML. The context state needs to be manually maintained to handle nested structures. The parsing process starts from startDocument to endDocument.

Aug 08, 2025 am 02:21 AM

Effective Java: Applying Best Practices in Your Codebase

UsetheBuilderPatternforclasseswithfourormoreparameterstoenhancereadability,preventerrors,andsupportimmutability;2.Favorcompositionoverinheritancetoreducecoupling,improvetestability,andavoidfragilebaseclassissues;3.AlwaysoverridehashCodewhenoverriding

Aug 08, 2025 am 02:18 AM

Understanding Phantom, Weak, and Soft References in Java

Strongreferencespreventgarbagecollectionaslongasthereferenceexists;2.Weakreferencesallowimmediatecollectionwhennostrongreferencesremain,idealforshort-livedcacheslikeWeakHashMap;3.Softreferencesareclearedonlyundermemorypressure,suitableformemory-sensi

Aug 08, 2025 am 01:59 AM

Event-Driven Architecture in Java using Apache Kafka

The core answer to implementing event-driven architecture (EDA) in Java using ApacheKafka is: by publishing events to topics through producers, consumers consume events asynchronously from topics, and leveraging Kafka's high throughput, persistence and fault tolerance to achieve system decoupling. 1. The producer uses KafkaProducerAPI to serialize data (such as JSON) and send it to the specified topic; 2. The consumer subscribes to the topic through KafkaConsumerAPI, pulls messages and processes it; 3. Use SchemaRegistry to manage data patterns to ensure compatibility; 4. The consumer group achieves horizontal expansion, and each partition is processed by a consumer within the group; 5. Practice includes error retry, dead letter queue, and idempotence.

Aug 08, 2025 am 01:53 AM

How to write to a CSV file in Java?

Using BufferedWriter is a simple method without external dependencies, but special character escapes need to be manually processed; 2. It is recommended to use the OpenCSV library, which can automatically handle complex situations such as quotation marks and commas to reduce errors; 3. If you do not use the library, you need to implement the field escape function to correctly handle values containing commas or quotes; in short, for simple data, you can use BufferedWriter to write line by line with try-with-resources, while for complex data, OpenCSV should be preferred to ensure correct formatting and development efficiency.

Aug 08, 2025 am 01:44 AM

How to sort a list in Java

Use Collections.sort() to sort the lists that implement the Comparable interface in natural ascending order; 2. Provide Comparator to implement custom sorting, such as sorting by string length or object fields; 3. Use Collections.sort(list, comparator) or list.sort(comparator) in Java 8 to sort the list in situ; 4. Use Stream.sorted() to generate a sorted new list without changing the original list; 5. Pay attention to null value processing and selecting appropriate sorting methods to meet immutability or custom order requirements.

Aug 08, 2025 am 01:43 AM

java List sorting

How to connect to a WebSocket in Java

ToconnecttoaWebSocketinJava,usetheJava-WebSocketlibraryforclient-sidecommunication.2.AddthelibraryviaMavenorGradleusingtheprovideddependency.3.CreateaclientbyextendingWebSocketClientandoverrideonOpen,onMessage,onClose,andonErrormethodstohandleevents.

Aug 08, 2025 am 01:34 AM

java

How Java's `HashMap` Works Internally

The working principle of HashMap is: 1. After the hashCode() of the key is processed by internal hash function, the bucket index is determined using bit operations; 2. The conflicting key-value pairs are initially stored in the bucket. When the linked list length exceeds 8 and the array length is ≥64, it is converted to a red and black tree; 3. When obtaining, it is called equals() to match the key; 4. When the number of elements exceeds the load factor (default 0.75)× capacity, expand the capacity to twice the original and reassign all elements - this process takes time, and it is recommended to preset capacity.

Aug 08, 2025 am 01:05 AM