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Implement a linked list in Java

The key to implementing a linked list is to define node classes and implement basic operations. ①First create the Node class, including data and references to the next node; ② Then create the LinkedList class, implementing the insertion, deletion and printing functions; ③ Append method is used to add nodes at the tail; ④ printList method is used to output the content of the linked list; ⑤ deleteWithValue method is used to delete nodes with specified values and handle different situations of the head node and the intermediate node.

Jul 20, 2025 am 03:31 AM

java

Java Virtual Threads and Goroutines Comparison

Both VirtualThreads in Java and Goroutines in Go are designed to improve the performance of high-concurrency scenarios, but the implementation mechanism and ecological support are different. 1. In terms of scheduling mechanism, VirtualThreads is managed by the JVM and scheduling through ForkJoinPool, while Goroutines is managed by the scheduler owned by Goruntime. It adopts the M:N model and has more mature scheduling capabilities; 2. In terms of startup cost, Goroutines starts faster and has a simpler syntax. It only requires gofunc(). Java uses Thread.ofVirtual().start() to create virtual threads, which is relatively cumbersome but more efficient than traditional threads.

Jul 20, 2025 am 03:27 AM

java

how to convert java object to json string using gson

The method of using Gson to convert Java objects into JSON strings is as follows: 1. Introduce Gson dependencies, add Maven or add implementation; 2. Create Java classes and instantiate objects; 3. Use Gson's toJson() method to convert objects. Notes include: ① Use @SerializedName annotation when the field names are inconsistent; ② Exclude or include null values through GsonBuilder; ③ Use .setDateFormat() to set date format; ④ Nested objects must ensure that each class has a default constructor and accessible fields. The whole process is simple and direct, and is suitable for most scenarios with clear structure.

Jul 20, 2025 am 03:09 AM

how to convert string to int in java

There are two main ways to convert strings to integers in Java: use Integer.parseInt() or Integer.valueOf(). The former is used to get the primitive type int, and the latter is used to get Integer objects. If the string contains non-numeric characters or is empty, a NumberFormatException will be thrown. Therefore, you need to check the format through regular expressions or use try-catch to catch the exception to handle the error. For values outside the int range, Long.parseLong() should be considered. The specific steps are as follows: 1. Use Integer.parseInt() to convert the string to int; 2. Use Inte

Jul 20, 2025 am 02:59 AM

Comparing Java Synchronized Block vs Method

When implementing thread synchronization in Java, the synchronized method and the synchronized block have their own applicable scenarios. 1. The synchronized method is simple to use, but the granularity is thick, which will lock the entire method body. This is used as the lock object by default, which is suitable for situations where the method logic is simple and all need to be synchronized; 2. The synchronized block is more flexible, only locks the specified code segment, and can customize the lock object, suitable for complex scenarios with small synchronization range or multiple locks; 3. The performance differences depend on the specific usage method. If the method contains a large amount of asynchronous code, the synchronization block can reduce unnecessary waits; 4. The usage suggestions include prioritizing synchronization blocks, avoiding excessive synchronization, and using private objects as locks as possible to improve

Jul 20, 2025 am 02:55 AM

java

how to create a file and directory in java

Creating files and directories in Java can be implemented in many ways, mainly including using File class and Files class. 1. Use the File class: create a file through createNewFile(), create a single-level or multi-level directory through mkdir() or mkdirs(); 2. Recommend using the Files class: create a file through createFile(), createDirectory() or createDirectories(); 3. Notes include path processing, permission checking, repeated creation judgment and cross-platform compatibility; 4. CreateTempFile() and createTempDirecto can be used

Jul 20, 2025 am 02:54 AM

Java JVM Thread States and Analysis

Thread state analysis in Java programs can be implemented through jstack commands, code acquisition and monitoring tools; JVM defines six thread states, and understanding their transformations can help troubleshoot performance problems, deadlocks and blocking problems. 1. RUNNABLE state means that the thread is executing or waiting for system resources. If the CPU is high, it may be a computing-intensive task or a dead loop; 2. BLOCKED state means that the thread cannot enter the synchronization block due to lock competition, so it is necessary to check the lock holder and competition situation; 3. WAITING/TIMED_WAITING state is thread waiting for notification or timeout, so it is necessary to check whether the wake-up mechanism is normal; 4. NEW/TERMINATED state is thread lifecycle state, usually no problem, but it may be due to thread pool

Jul 20, 2025 am 02:51 AM

Implementing Micro Frontends with Java Backend

The micro front-end architecture realizes multi-team collaboration and flexible deployment by splitting the front-end applications into multiple independent modules. The core combination methods include using WebComponents or iframes to embed sub-applications, dynamic loading using routing mapping, and coordinated communication through container applications; the Java back-end serves as API provider and service governance support, and uses RESTfulAPI to divide independent path space, unified authentication mechanism, introduces the gateway layer to process request routing, and configures CORS policies; in terms of deployment, it can be integrated through static resource hosting, decoupling dependencies in the construction stage, and Docker containerization; it is recommended to use local proxy, enable hot updates, simulate micro front-end environments and unified log formats during development and debugging.

Jul 20, 2025 am 02:48 AM

java backend micro frontend

Advanced Java Debugging with VisualVM and JConsole

The key to Java debugging is to master the use of VisualVM and JConsole tools. 1. VisualVM is a graphical troubleshooting tool that integrates multi-JDK tools. It can view the JVM running status in real time, analyze hotspot methods and frequent objects through "Sampler", and supports remote monitoring configuration and plug-in extensions. 2. JConsole is suitable for quickly viewing memory, threads, and class loading, and can detect deadlocks and observe GC frequency. 3. It is better to use the two in combination: first use JConsole to observe the exception, then deeply analyze the performance bottlenecks through VisualVM, and it is recommended to grab heapdump for further diagnosis.

Jul 20, 2025 am 02:43 AM

java debug

Reactive Programming with Java WebFlux Best Practices

Four key points to pay attention to when using JavaWebFlux for responsive programming: 1. Avoid blocking operations, especially I/O. You should use map, flatMap and other chain processing, and use R2DBC to replace JDBC; 2. Use schedulers reasonably, use parallel() for CPU-intensive use, and use boundedElastic() for blocking I/O; 3. Unified error handling, use onErrorResume, onErrorReturn and doOnError to clearly deal with exceptions; 4. Use backpressure mechanisms such as limitRate() to control data flow to prevent memory overflow.

Jul 20, 2025 am 02:37 AM

How to convert a List to an Array in Java?

There are three common methods to convert List to Array in Java: 1. Use the toArray() method, which is suitable for common object types such as strings and integers, such as String[]array=list.toArray(newString[0]); 2. Manual conversion, which is suitable for basic data types, and needs to create an equal-length array and traverse the assignment, such as int[]array=newint[list.size()] and unboxing through loop; 3. Use StreamAPI, which is suitable for scenarios that require mapping or filtering, such as list.stream().mapToInt(Integer::intValue).toArr

Jul 20, 2025 am 02:36 AM

list array

what is the static keyword in java

ThestatickeywordinJavameanssomethingbelongstotheclassitself,nottoinstances;1.Staticvariablesaresharedamongallinstancesandaccessedviatheclassname,suchasCar.numberOfCars;2.Staticmethods,likeMath.sqrt(),canbecalledwithoutaninstanceandonlyaccessstaticmem

Jul 20, 2025 am 02:32 AM

Java JVM Metaspace Management and Tuning

To manage and tune Metaspace, you can first check the usage of Metaspace through jstat, jcmd, VisualVM and other tools; secondly, set -XX:MaxMetaspaceSize and -XX:MetaspaceSize to control its size; when troubleshooting class loading leakage, you should check the class loader distribution and heap dump; finally, Metaspace recycling depends on FullGC, and GC can be manually triggered to observe the recycling effect if necessary.

Jul 20, 2025 am 02:30 AM

java

Java Security for Deserialization Vulnerabilities

Java deserialization vulnerability refers to the risk of remote code execution that may be triggered when deserializing operations on untrusted data. 1. Vulnerability principle: When a program uses ObjectInputStream to deserialize untrusted data, sensitive methods in maliciously constructed classes (such as readObject()), resulting in arbitrary code execution; 2. Attack method: The attacker initiates an attack by constructing GadgetChain, using RMI/JNDI communication mechanism or third-party libraries (such as CommonsCollections); 3. Utilization conditions: The application receives external input and deserializes, the class path has available classes and no whitelist verification; 4. Preventive measures: Avoid directly processing user input

Jul 20, 2025 am 02:10 AM