97久久久久人妻精品区一,av天堂网avtt,а√中文在线资源库

Article Tags

Home

Technical Articles

Java

Tutorial on calculating word points based on character scoring in Java

This tutorial is intended to guide how to correctly implement the function of calculating the total score of a word based on character points in Java. The article will explain in detail the common misuse of switch statements in the original code and provide solutions to map character points by traversing string characters and correctly using switch statements or Map collections. The tutorial will also cover key considerations such as file reading, case processing, and code optimization to ensure that readers can build a robust and efficient word scoring system.

Aug 12, 2025 am 07:03 AM

HashMap iteratively implements the score rating system

This article describes how to implement a simple grade rating system in Java using HashMap. By storing the score level as a key and the score threshold as a value in HashMap, it is easy to find the corresponding level based on the input score. The article provides detailed code examples and explains how to handle exception input, helping readers understand the iteration of HashMap and its application in practical problems.

Aug 12, 2025 am 06:24 AM

Functional Programming Concepts in Modern Java

Java supports core concepts of functional programming: implement first-class functions and higher-order functions through functional interfaces and lambda expressions; 2. Advocate immutability and pure function design to reduce side effects; 3. Provide java.util.function built-in interfaces such as Function and Predicate to improve code consistency; 4. StreamAPI implements declarative data processing, supporting chain calls and lazy evaluation; 5. Method reference simplifies lambda expressions of existing methods; 6. Optional class safely handles null values to avoid NullPointerException. These features make Java code more concise, readable, robust and easy to program concurrently.

Aug 12, 2025 am 06:20 AM

java functional programming

How to convert a char to a string in Java

UseString.valueOf(ch)forclarityandsimplicity;2.UseCharacter.toString(ch)forconsistencywithwrapperclasses;3.Avoid"" chinperformance-sensitivecodedespiteitssimplicity;4.UsenewString(newchar[]{ch})ifcreatingfromasingle-elementarray;5.UseString

Aug 12, 2025 am 06:08 AM

java character conversion

How to filter a collection in Java

Using Java8's StreamAPI is the best way to filter collections. 1. Call stream() to convert the collection into a stream; 2. Use filter() to pass in Predicate conditions; 3. Collect the results into List, Set or array through collect(); this method does not modify the original collection, supports chain calls, and the code is concise and efficient, and is recommended for modern Java development.

Aug 12, 2025 am 05:58 AM

How to parse a date in Java?

The Java.time package introduced by Java 8 should be used first to parse dates because it is thread-safe and easy to use; for ISO-8601 formats such as 2024-05-15, you can use LocalDate.parse() directly without specifying a formatter. The custom format needs to be defined through DateTimeFormatter.ofPattern() and parsed after defining the pattern, supporting datetime and time zone resolution. At the same time, DateTimeParseException should be captured to handle invalid input, avoiding the use of old SimpleDateFormat and Date classes, because they are not thread-safe and error-prone. If you must use it, you need to pay attention to synchronization issues and can be passed

Aug 12, 2025 am 05:56 AM

java 日期解析

How to use the try-with-resources statement in Java

Thetry-with-resourcesstatementinJavaautomaticallyclosesresourcesthatimplementAutoCloseableorCloseable,ensuringefficientresourcemanagement.1.ItwasintroducedinJava7toeliminatetheneedforexplicitfinallyblockstocloseresources.2.Resourcesaredeclaredinthetr

Aug 12, 2025 am 05:31 AM

What is a String in Java?

AStringinJavaisanobjectrepresentingtext,notaprimitivetype,andishandledviatheStringclassinthejava.langpackage.1.Stringsareimmutable,meaningoncecreated,theycannotbechanged;operationslikeconcatenationcreatenewStringobjectsinsteadofmodifyingtheoriginal.2

Aug 12, 2025 am 05:29 AM

Flexible search: numerical acquisition strategy based on partial keys in Java Properties files

In Java development, when it is necessary to obtain values based on keys from java.util.Properties files, it is usually required to provide an exact key name. However, in the case where only part of the key information is known (such as part of the substring of the key), the standard method cannot directly meet the needs. This article will introduce a practical solution in detail: by traversing all attribute keys and combining string matching methods, we can achieve flexible search and value acquisition of some keys, and at the same time explore its applicable scenarios, performance considerations and potential optimization strategies.

Aug 12, 2025 am 05:21 AM

How to work with BigDecimal for precise calculations in Java

To use BigDecimal to perform decimal operations accurately, you must use a string constructor, specify a rounding mode, and compare with compareTo; 1. Create an object with newBigDecimal("0.1") or BigDecimal.valueOf(0.1); 2. Call divide(a,b,4, RoundingMode.HALF_UP) and other explicitly specify the accuracy and rounding mode when performing division; 3. Use setScale(2, RoundingMode.HALF_UP) to control the number of decimal places; 4. Use compareTo() to determine the equality of the values instead of equals(); 5. Avoid

Aug 12, 2025 am 04:26 AM

Creating Custom Annotations in Java for Metaprogramming

Define custom annotations using the @interface keyword, which can contain member variables such as value, assignedTo and priority, and control their behavior and life cycle through meta annotations such as @Target, @Retention, @Documented, @Inherited and @Repeatable; 2. When using @Repeatable, you need to define container annotation such as TodoList to support reuse; 3. Process annotations at runtime through reflection, use getAnnotationsByType method to obtain annotation information and execute corresponding logic; 4. Implement the annotation of AbstractProcessor at compile time

Aug 12, 2025 am 03:16 AM

How to create a REST controller in Java with Spring Boot

Use SpringInitializr to create a project and add SpringWeb dependencies; 2. Create a User model class to define the data structure; 3. Use @RestController and @RequestMapping to create a controller containing @GetMapping, @PostMapping, @PutMapping, @DeleteMapping methods; 4. Run the application and test the API endpoints through curl or Postman. SpringBoot automatically handles JSON serialization and request routing, thereby quickly building a fully functional REST controller.

Aug 12, 2025 am 03:14 AM

What are the main principles of object-oriented programming in Java?

Thefourmainprinciplesofobject-orientedprogramminginJavaareencapsulation,inheritance,polymorphism,andabstraction.Encapsulationbundlesdataandmethodswithinaclassandrestrictsdirectaccesstointernaldetailsusingaccessmodifiers,ensuringdataintegrity—forexamp

Aug 12, 2025 am 02:51 AM

java Object-Oriented Programming

How to use the StringBuilder class in Java

Use StringBuilder to efficiently process variable strings. 1. Creation methods include: empty construction, with initial string or specified capacity; 2. Common operations include: append() append, insert() insert() insert, replace() replacement, delete() delete() deletion, reverse() inversion and setLength() setting length; 3. After the modification is completed, you need to call toString() to convert to String; 4. Better than String splicing in single thread to avoid a large number of temporary objects; 5. Non-thread safe, StringBuffer should be used in multi-thread scenarios. Therefore, when frequently modifying strings, you should give priority to using StringBuilder to improve

Aug 12, 2025 am 02:40 AM