
What are different garbage collectors?
There are 5 main types of garbage collectors in Java, each suitable for different scenarios. 1. SerialGC single-threaded operation, suitable for small applications and single-core systems; 2. ParallelGC multi-threaded processing, focusing on throughput, suitable for batch tasks; 3. CMS concurrent mark clearance, reducing latency but increasing resource consumption, suitable for response time-sensitive applications; 4. G1 partition recycling, balancing throughput and latency, suitable for large-scale memory; 5. ZGC and Shenandoah support ultra-low latency and TB memory, suitable for real-time high-load services. When choosing, it must be determined based on application scale, performance requirements and hardware conditions.
Jul 04, 2025 am 01:26 AM
Implementing Dependency Injection in Java Applications
Dependency injection (DI) achieves decoupling through the dependencies of external control objects, improving code testability, maintainability and flexibility. 1. DI is a design pattern, and the core is to create it by external incoming dependencies rather than objects themselves; 2. Common injection methods include constructor injection (most commonly used), Setter injection (suitable for optional dependencies), and field injection (not recommended); 3. DI can be implemented manually, such as passing dependencies through constructors; 4. Using Spring framework can simplify dependency management, and automatically handle dependencies through @Component and @Autowired annotations; 5. Pay attention to avoiding complex constructors and bean conflicts, not all classes need framework management. Mastering these key points can make it more efficient in Java
Jul 04, 2025 am 01:14 AM
What are Records in Java?
JavaRecords is a feature introduced by Java16 to simplify the definition of immutable data classes. It automatically generates common methods such as construction methods, getter methods, toString(), equals() and hashCode() through a line of code to reduce redundant code and improve development efficiency; its advantages include simplicity, immutability, thread safety and ease of debugging; suitable for packaging when returning multiple values ??in DTO, JSON serialization, configuration classes and functional programming; but it is not suitable for scenarios where object state needs to be frequently modified or other classes need to be inherited; in addition, record can implement interfaces and support the addition of static factory methods to enhance readability, such as using Person.of("T
Jul 04, 2025 am 12:54 AM
Managing Dependencies with Java Maven or Gradle
In Java projects, the following key points must be mastered: 1. Understand dependency transfer and scope, and reasonably set the scope of compile, runtime, test, etc. to avoid redundant dependencies; 2. Unify the version number, centrally manage it through Maven's properties or Gradle's versions.gradle, and use BOM to unify the dependency set version; 3. Use tools such as mvndopendency:tree or gradled dependencies to troubleshoot conflicts, and resolve conflicts by explicitly specifying the version, excluding dependencies or force strategies; 4. In multi-module projects, Maven uses the parent POM and G
Jul 04, 2025 am 12:43 AM
Immutability of String Objects in Java Explained
StringsinJavaareimmutableforperformance,security,andmemoryefficiency.1.ImmutabilityallowstheJVMtooptimizestringpooling,reducingmemoryusagebyreusingidenticalstringobjects.2.Securityisenhancedbecausemutablestringscouldbealteredunexpectedlywhenpassedtom
Jul 04, 2025 am 12:42 AM
Introduction to Java Native Interface (JNI) Use Cases
Common usage scenarios for JNI include improving the execution efficiency of performance-sensitive parts, accessing operating system or hardware-specific features, reusing existing local library resources, and enhancing security and anti-reverse protection. 1. For high-performance tasks such as image processing, encryption and decryption, C/C can be used to implement key logic through JNI to improve efficiency, but attention should be paid to cross-language call overhead; 2. When accessing device drivers, sensor data or system APIs is required, it can be implemented with the help of the JNI call platform related local libraries, and compatibility issues should be considered; 3. In order to reuse existing C/C code assets, it can be encapsulated through JNI for Java application calls to reduce duplicate development, but a reasonable interface should be designed; 4. Placing the key logic at the native layer can increase the reverse difficulty
Jul 04, 2025 am 12:26 AM
What is `BufferedWriter`?
BufferedWriter is a class in Java for efficient writing character streams. It reduces the number of I/O operations through a buffering mechanism and improves performance. 1. When creating, you need to pass in FileWriter or other Writer subclasses; 2. Common methods include write() to write strings, newLine() to break lines, flush() to force refresh, close() to close() to close the stream; 3. Use try-with-resources to ensure automatic closing of the stream; 4. Appropriately refresh, handle exceptions, and prioritize large amounts of data writing.
Jul 03, 2025 am 02:24 AM
What is type erasure?
TypingasureexistsinlanguagoezeslikejavaandwifttomaintainbackwardcompatibilityandruntimeefficiCybyremoving generative type formation runningime.1.Tensurescompile-TimetypesafetywoodburdeningTeRuntime-TimeTata.2.injava-TimeTata.2.injavaTueCileCilePedata.2.
Jul 03, 2025 am 02:23 AM
How to write to a file in Java?
Writing files in Java can be implemented in many ways, mainly including the following methods: 1. Use FileWriter and BufferedWriter to create a BufferedWriter object and call the write method to write content, supporting append mode and automatic resource management; 2. Use the Files class (recommended), and write string or list content at one time through the Files.write method, supporting overwrite and append mode, and specifying character sets; in addition, you need to pay attention to common problems such as paths, encodings, permissions and newlines to ensure that the file is written correctly.
Jul 03, 2025 am 02:22 AM
Difference between `volatile` and `synchronized`?
volatileensuresvisibilityofvariablechangesacrossthreadsbutlacksatomicity,whilesynchronizedprovidesbothvisibilityandatomicity.Usevolatileforsingleoperationswithoutcompoundactions,likesettingflags.Usesynchronizedformulti-stepoperationsrequiringmutualex
Jul 03, 2025 am 02:20 AM
What is a JAR file?
AJARfileisapackagedbundleofJavafilesusedforeasierdistribution.Itcontainscompiledclassfiles,amanifestfilewithmetadata,andotherresources.Themanifestdefineskeydetailslikethemainclasstorun.DevelopersuseJARsfororganization,portability,securitythroughsigni
Jul 03, 2025 am 02:19 AM
What is the `toString` method?
The toString method is used to return the string representation of the object, which is easy to debug and display. The default implementation information is limited, so developers often rewrite this method to provide more meaningful information. For example, in Java, return "Person{name='John',age=30}" by overwriting toString; define the toString method in JavaScript to achieve similar effects. Application scenarios include debugging, logging, user output and collection display. It is recommended to add a toString method for custom classes to keep the output concise and not throw exceptions.
Jul 03, 2025 am 02:19 AM
What is method overloading?
MethodOverloading means that multiple methods of the same name can be defined in the same class, but the parameters of these methods must be different. The core is "the method name is the same, the parameters are different", which is manifested as different number, type or order of parameters; the return value type cannot be used as the basis for overloading. For example, multiple add methods can be defined in Java to handle different types and quantities of inputs. The main purpose of using method overloading is to improve the readability and reusability of the code, so that the caller does not need to remember multiple method names. Common application scenarios include constructor overloading, tool-like method adaptation, etc. Notes include: Avoid excessive overloading, do not distinguish methods based on return values ??alone, and pay attention to problems that may be caused by automatic type conversion. Support method
Jul 03, 2025 am 02:18 AM
What are common built-in annotations?
Common built-in annotations in Java are mainly divided into three categories: annotations used by the compiler, annotations used to help the tool process, and annotations available at runtime. 1. @Override is used to rewrite the parent class method. If the parent class method is not really overwritten, the compiler will report an error. It is suitable for scenarios where the method is rewrite in inheritance; 2. @Deprecated marks the element is outdated, prompting developers to avoid using it and may be removed in the future. It is usually used with the @deprecated of Javadoc; 3. @SuppressWarnings suppresses compiler warnings, suitable for situations where specific "security" warnings are ignored, but they should be used with caution to prevent potential problems; 4. Meta annotations include @Retention and @Ta
Jul 03, 2025 am 02:18 AM
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