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Identifying and Preventing Memory Leaks in Java Applications

Memory leaks in Java refer to objects that are no longer used but cannot be recycled by GC because the reference is not released. Common scenarios include the collection class not being cleaned, the listener not being logged out, the cache is not invalidated, and the internal class holding external class references, etc. 1. Uncleaned collection classes will cause continuous memory occupancy. The solution is to clean or use weak references regularly; 2. The listener and callbacks are not logged out, and the weak reference mechanism should be actively removed or used; 3. The internal class holds external class references to static internal classes and manually manage the references; 4. The cache has not set an expiration strategy, it is recommended to use mature cache libraries such as Caffeine or Ehcache; in addition, you should also pay attention to log objects, ThreadLocal usage and ClassLoader uninstallation issues. To identify memory leaks, you should combine them with the heap.

Jul 08, 2025 am 12:01 AM

Effective Use of Java Enums and Best Practices

Java enumerations not only represent constants, but can also encapsulate behavior, carry data, and implement interfaces. 1. Enumeration is a class used to define fixed instances, such as week and state, which is safer than strings or integers; 2. It can carry data and methods, such as passing values ??through constructors and providing access methods; 3. It can use switch to handle different logics, with clear structure; 4. It can implement interfaces or abstract methods to make differentiated behaviors of different enumeration values; 5. Pay attention to avoid abuse, hard-code comparison, dependence on ordinal values, and reasonably naming and serialization.

Jul 07, 2025 am 02:43 AM

Best Practices

Choosing Between Java ExecutorService and ForkJoinPool

ExecutorService is suitable for managing independent tasks, such as HTTP requests or timing tasks, executed through fixed or cache thread pools; ForkJoinPool is suitable for split-merged recursive tasks, using work theft to improve CPU utilization. 1.ExecutorService is flexible in control and suitable for tasks-independent scenarios; 2.ForkJoinPool is used for partitioning and governance problems, such as big data processing; 3. If the task needs to be disassembled and merged, choose ForkJoinPool; 4. Otherwise, use ExecutorService first, because it is simpler and more intuitive.

Jul 07, 2025 am 02:43 AM

Effective Resource Management with Java's try-with-resources

Java7 introduces try-with-resources to ensure that resources are automatically closed and avoid leakage. 1. The resource needs to implement the AutoCloseable or Closeable interface and declare it in try brackets; 2. Multiple resources are closed in reverse order in declarations to prevent errors in closing dependencies; 3. If the try block and close() throw exceptions at the same time, the exceptions in the try are retained and the close exceptions are suppressed, and can be viewed through getSuppressed(); 4. The resource scope is limited to the try block and cannot be accessed in catch or finally; 5. Avoid manually repeatedly closing resources to prevent null pointer exceptions; 6. Note that nested resources may need to be manually released and cannot be completely dependent on them.

Jul 07, 2025 am 02:41 AM

Exploring the Java Collections Framework Hierarchy

The core of the Java collection framework is the Collection interface and the Map interface, which form the basis of the entire framework. 1. The Collection interface is the root interface of all collection classes. Its three sub-interfaces List, Set and Queue are used to process ordered and repeatable data (such as ArrayList and LinkedList), unordered and unrepeatable data (such as HashSet and TreeSet), and first-in-first-out queue operations (such as LinkedList and PriorityQueue). 2. Although the Map interface does not belong to the Collection system, it is also an important part of the framework and is used to store key-value pair data. Common implementations include Ha

Jul 07, 2025 am 02:39 AM

java collection collection framework

Best Practices for Using Enums in Java

In Java, enums are suitable for representing fixed constant sets. Best practices include: 1. Use enum to represent fixed state or options to improve type safety and readability; 2. Add properties and methods to enums to enhance flexibility, such as defining fields, constructors, helper methods, etc.; 3. Use EnumMap and EnumSet to improve performance and type safety because they are more efficient based on arrays; 4. Avoid abuse of enums, such as dynamic values, frequent changes or complex logic scenarios, which should be replaced by other methods. Correct use of enum can improve code quality and reduce errors, but you need to pay attention to its applicable boundaries.

Jul 07, 2025 am 02:35 AM

java Enums

What is method overloading vs overriding in Java?

The core difference between method overloading and rewriting is that overloading is to implement the same name method through different parameter lists in the same class, while rewriting is the method of the subclass redefining the parent class. Specifically: 1. Method overload requires the same method name but different parameters (number, type or order), which is used to improve code readability and flexibility, such as the add method in the Calculator class; 2. Method rewriting requires the method name, parameters and return types to be exactly the same, which is used to implement runtime polymorphism, such as Dog class rewrites Animal's sound method; 3. Overloading is a compile-time polymorphism, while rewriting is a runtime polymorphism; 4. Overloading can be used for static methods, while rewriting is only applicable to instance methods.

Jul 07, 2025 am 02:29 AM

Method overloading Method overriding

Deploying Java Applications to Cloud Platforms

When deploying Java applications to cloud platforms, you need to pay attention to the following key points: 1. Prepare WAR or JAR format packaging files to avoid including local configurations; 2. Choose a suitable cloud platform and deployment method, such as PaaS, IaaS or container services; 3. Use environment variables to manage external dependency configurations to avoid hard coding; 4. Pay attention to time zone settings and log monitoring to ensure stable operation of the application.

Jul 07, 2025 am 02:29 AM

java cloud platform

Asynchronous Programming Techniques in Modern Java

Java supports asynchronous programming including the use of CompletableFuture, responsive streams (such as ProjectReactor), and virtual threads in Java19. 1.CompletableFuture improves code readability and maintenance through chain calls, and supports task orchestration and exception handling; 2. ProjectReactor provides Mono and Flux types to implement responsive programming, with backpressure mechanism and rich operators; 3. Virtual threads reduce concurrency costs, are suitable for I/O-intensive tasks, and are lighter and easier to expand than traditional platform threads. Each method has applicable scenarios, and appropriate tools should be selected according to your needs and mixed models should be avoided to maintain simplicity

Jul 07, 2025 am 02:24 AM

java Asynchronous programming

How to prevent Deadlock in Java?

The key to avoiding Java deadlocks is one of the four necessary conditions for breaking the deadlock. 1. Avoid the "request and hold" state. You can retry by applying for all resources at once or releasing existing resources, and ensure that threads access multiple locks in the same order; 2. Introduce the hierarchical order of locks, assign numbers to each lock and require threads to lock in the numbering order to prevent loop waiting; 3. Use the ReentrantLock.tryLock() method to cooperate with the timeout mechanism to try to acquire the lock within a specified time, and release the existing lock to avoid blocking if it fails; 4. Use jstack, VisualVM and other tools to regularly detect potential deadlocks to assist in troubleshooting and monitoring the use of locks.

Jul 07, 2025 am 02:19 AM

java deadlock

What is an anonymous inner class?

Anonymous internal classes are used in Java to create subclasses or implement interfaces on the fly, and are often used to override methods to achieve specific purposes, such as event handling in GUI applications. Its syntax form is a new interface or class that directly defines the class body, and requires that the accessed local variables must be final or equivalent immutable. Although they are convenient, they should not be overused. Especially when the logic is complex, they can be replaced by Java8's Lambda expressions.

Jul 07, 2025 am 02:18 AM

java anonymous inner class

How to work with dates and times in Java 8 (java.time)?

It is recommended to use the java.time package to handle dates and times in Java 8 and above. 1. LocalDate and LocalTime are used for dates and times without time zones, such as 2025-04-05 and 14:30:45 respectively; 2. Use now() to get the current date or time, and of() to create a specified date or time; 3. Common operations include adding and subtracting days, months, etc., and the object is immutable, and each operation returns a new instance; 4. LocalDateTime combines date and time but no time zone, ZonedDateTime supports time zone; 5. Use ZoneId to define the time zone and convert it through atZone(), and use withZoneSameInstan

Jul 07, 2025 am 02:15 AM

date time Java 8+

Understanding Java ClassLoader Hierarchy and Delegation Model

The JavaClassLoader hierarchy consists of a parent-child structure consisting of Bootstrap, Extension and ApplicationClassLoader. The delegate priority model is adopted to ensure the consistency and security of core classes. Class loading problems are common in classpath errors or class loader isolation. When troubleshooting, you need to check dependencies, logs and use -verbose:class parameters; custom ClassLoader needs to inherit and rewrite findClass() to avoid duplicate loading and pay attention to the hot replacement mechanism.

Jul 07, 2025 am 02:09 AM

java

Persistent Data Storage using Java JPA and Hibernate

JPA is a Java persistence specification, and Hibernate is its commonly used implementation. 1. JPA defines object and database mapping standards, and Hibernate is responsible for specific operations. 2. Entity classes map table structures through @Entity, @Table, @Id, @GeneratedValue, etc. 3. The association relationship is processed through annotations such as @OneToMany, @ManyToOne, etc., and pay attention to mappedBy and cascading configuration. 4. In SpringBoot, you can quickly complete persistence operations by configuring data sources and using SpringDataJPA.

Jul 07, 2025 am 02:05 AM

java