Q11: Discuss HashMap resizing in JDK 1.8 When putting an item, if the map finds that the current bucket occupancy has exceeded the proportion specified by the Load Factor, then a resize will occur. The resizing process simply means expanding the bucket to twice its original size, then recalculating the index and putting the nodes in the new… Read More »
Q6. How to specify the initial value of the Hashmap in JDK 1.8? Simply use the following declaration. Q7. How to ensure the initial value is 2 to the power of n? In order to ensure the initial value is 2 to the power of n, we have to leverage an algorithm that first finds the bit with… Read More »
Nowadays, SpringCloud-based microservice development is becoming more and more popular, and various open-source projects on the Internet are emerging endlessly. We can refer to open source projects to implement many out-of-the-box functions in actual work, but we must abide by certain conventions and specifications. This post combines some of the problems encountered in our actual development to sort… Read More »
Q1. Please breifly discuss Hashmap in JDK 1.8 Hashmap is a map interface based on hash table implementation. This implementation provides all optional mapping operations and allows empty values (value) and empty keys (key). (The HashMap class is roughly equivalent to Hashtable, but it is thread-unsafe and allows null values) This class cannot guarantee the order of mapping;… Read More »
In our daily development, we may casually expose the database password directly in plaintext in the configuration file, which can be done in the development environment, but it is not recommended to do so in the production environment. After all, security is not trivial. No one knows which day the password is somehow leaked. Today we will talk… Read More »
What is CSRF? CSRF is an abbreviation of Cross-Site Request Forgery. It is a script that can send HTTP requests. The victim can be disguised to send a request to the website to achieve the purpose of modifying the website data. CSRF can steal all user cookies after the user clicks a link so that the account is… Read More »
Introduction R2DBC is an asynchronous, non-blocking relational database connection specification. Although some NoSQL database vendors provide reactive database clients for their databases, for most projects, migrating to NoSQL is not an ideal choice. This prompted the birth of a universal, responsive relational database connection specification. As a relational database with a huge user base, MySQL also has a… Read More »
Idempotency Idempotency means that no matter how many times you execute the request, the result is the same. Speaking of idempotency, you have to say repeated submission. You click the submit button continuously. In theory, this is the same piece of data. The database should only store one item but store multiple items, which violates idempotency. Therefore, we… Read More »
Questions: Describe the Java garbage collection mechanism. What is GC? Why do we use GC? Advantages and principles of garbage collection, and describe two recovery mechanisms. What is the basic principle of the garbage collector? Can the garbage collector reclaim memory immediately? What’s the way to actively notify the virtual machine for garbage collection? What are the reference… Read More »
Heap Java’s heap is a runtime data area, and objects of classes allocate space from the heap. These objects are created by instructions such as new and destroyed by the garbage collector. The advantage of the heap is that it can allocate memory space dynamically. It is unnecessary to tell the compiler how much memory space is needed… Read More »
String is an elementary and essential class in the Java language, which provides various basic logic for constructing and managing strings. It is a typical Immutable class, declared as a fnal class, and all attributes are also fnal. Because of its immutability, actions such as stitching and cutting strings will generate new String objects. Due to the universality… Read More »