
What is the exception hierarchy?
Exception hierarchy refers to the exception type organized in a tree structure in programming, and its core is the base class such as Python's Exception or Java's Throwable. 1. The exception hierarchy starts with BaseException, Exception, etc., and derives more specific exceptions such as IOException or NullPointerException. 2. Through the hierarchy, developers can accurately catch specific exceptions, such as first catching ValueError and then handling general exceptions. 3. When customizing exceptions, you should inherit the appropriate base class. For example, creating AppError as the basis for custom errors, and further refine DatabaseError.
Jun 28, 2025 am 12:55 AM
How to handle stack overflow errors?
Stack overflow errors are usually caused by recursion without termination or excessive local variables. When checking, you should first check whether the recursion logic is correct, ensure that there are clear termination conditions and gradually approach the termination point, and use loops when necessary; secondly, consider adjusting the thread stack size, but be careful to avoid wasting resources; finally, avoid excessively large local variables in the function and use dynamic allocation instead. 1. The main reason for stack overflow is infinite recursion or local variables occupy too much stack space. 2. Repair recursive logic requires termination judgment, such as adding n to factorial function
Jun 28, 2025 am 12:47 AM
What is the strictfp keyword?
The strictfp keyword is used to ensure that floating point operations in Java produce the same results on all platforms, which achieve consistency by forcing compliance with the IEEE754 standard. 1. It limits the accuracy of intermediate floating point results to float or double type to avoid slight errors caused by hardware differences; 2. It can be applied to class or method levels, but not to variables or constructors; 3. It is suitable for financial, scientific computing and other scenarios that require cross-platform consistency, which may slightly affect performance. This keyword is usually not required if precise control of floating point behavior is not required.
Jun 28, 2025 am 12:45 AM
What are bitwise operators?
Bitwiseoperatorsmanipulateindividualbitsofbinarynumbers.TheyperformoperationslikeAND(&),OR(|),XOR(^),NOT(~),leftshift(),enablingprecisecontroloverspecificbitswithoutaffectingothers.Theseoperatorsareusedinrealcodetoefficientlymanagesettings,flags,
Jun 28, 2025 am 12:26 AM
What is a package in Java?
PackagesinJavaorganizecodeintounitstopreventnamingconflictsandimproveorganization.1.Packagesgrouprelatedclasses,interfaces,andsub-packages.2.Theyavoidnameclashesbyallowingsame-namedclassesindifferentpackages.3.Theycontrolaccessusingpackage-privatevis
Jun 28, 2025 am 12:16 AM
How to use Gradle build tool?
The key to building a project with Gradle is to understand its structure and commands. After creating the project manually or with the IDE, the core files build.gradle and settings.gradle configure dependencies and subprojects respectively. Gradle construction is divided into three stages: initialization, configuration, and execution. Common tasks such as build and test can be viewed and run through gradletasks. Custom tasks can be defined in build.gradle, such as taskhello output text. Adding dependencies is completed in dependencies block, plugins such as java and application are introduced through plugins blocks, and improving functions such as running Java programs directly. Recommended
Jun 28, 2025 am 12:14 AM
What is the native keyword?
Nativekeyword refers to the keyword system natively supported by the platform, which is commonly found in ASO and advertising. It directly affects exposure and ranking, can be optimized without third-party tools, and is recognized by the platform first. Specific usage methods include: 1. GooglePlay crawls keywords through titles, subtitles, and descriptions; 2. AppStore provides 100-character keyword fields, separated by commas; 3. Advertising platforms such as Facebook and TikTok fill in keyword tags to match users. Optimization methods include basic research, avoiding stacking, regular inspection of the results, and combining competitive product analysis.
Jun 27, 2025 am 01:50 AM
What is the `finally` block?
Finally blocks are used to execute critical code that must be run regardless of whether an exception occurs, and are often used to clean up resources. Its core functions include: 1. Ensure that resources such as file, database connection are closed; 2. Ensure execution in different scenarios (such as exception thrown, early return); 3. Avoid resource leakage and improve program reliability. For example, after reading a file in Java, use finally to close the stream, even if there is a return statement in the try or catch, finally executes before it returns. When using it, please note: do not use return/break/continue in finally to avoid covering up exceptions; some languages ??such as Python recommend using with statements instead of final
Jun 27, 2025 am 01:49 AM
How does Java work?
The running mechanism of Java programs mainly includes compilation into bytecode, JVM execution and automatic memory management. First of all, Java code is compiled into platform-independent bytecode (.class file) through javac, realizing "write once, run everywhere". Next, the JVM loads the bytecode and interprets it by the execution engine or compiles it into machine code through JIT. At the same time, the JVM is also responsible for class loading, memory management and garbage collection. Then, the class loader (ClassLoader) loads class files from disk or network, and the runtime data area includes heap, stack, method area, etc. for data storage for program operation. Finally, the garbage collection mechanism automatically recognizes and frees object memory that is no longer in use, avoiding the complexity of manual memory management. The whole process starts
Jun 27, 2025 am 01:43 AM
What is a local inner class?
AlocalinnerclassinJavaisahelperclassdefinedwithinablockofcode,typicallyamethod,andisusefulforencapsulatinglogicthat'sonlyrelevantinthatspecificcontext.Itcanaccessouterclassmembersandfinaloreffectivelyfinallocalvariablesbutcannothaveaccessmodifiersors
Jun 27, 2025 am 01:41 AM
What is `FileInputStream`?
FileInputStreaminJavaisusedtoreadbinarydatafromafile.Itbelongstothejava.iopackageandisidealforreadingrawdatasuchasimages,audiofiles,orserializedobjects.1.Itworksbyopeningaconnectiontothefileandreadingbyteseitheroneatatimeorinbatchesusingmethodslikere
Jun 27, 2025 am 01:39 AM
What is the `break` statement?
Thebreakstatementterminatesloopsorswitchcasesearly.1.Inloopslikeforandwhile,breakstopsexecutionandmovestothecodeaftertheloop,usefulforexitingonceaconditionismet.2.Inswitch-likestructures(e.g.,JavaScript’sswitchorPython’smatch-case),breakpreventsunint
Jun 27, 2025 am 01:34 AM
What is the JRE?
JRE is the environment required to run Java programs, it contains JVM, class libraries, and startup tools. 1. JVM is the core of executing Java code; 2. The Java class library provides network, graphics and file processing functions; 3. The startup tool is used to run Java applications smoothly. JRE is aimed at ordinary users, while JDK includes JRE and development tools, suitable for developers. If the system does not have Java preinstalled, JRE needs to be installed manually. Common prompts include program errors or browser prompts. Installing JRE today is usually done as part of the JDK.
Jun 27, 2025 am 01:34 AM
What is the wrapper class concept?
Awrapperclassencapsulatesaprimitivedatatypetoprovideadditionalfunctionality.Itallowsprimitivestobetreatedasobjects,enablesuseofusefulmethodsforconversionandmanipulation,supportsnullvalues,andisessentialwhenworkingwithcollectionsorgenerictypes.However
Jun 27, 2025 am 01:24 AM
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