Programmer Think

1, Usage scenarios for delayed tasks 1. The order was placed successfully and was not paid for 30 minutes. Payment timeout, automatic cancellation of order 2. The order was signed, and no evaluation was conducted 7 days after signing. The order timeout is not evaluated, and the system defaults to high praise 3. The order was placed successfu ...

The initial brush force deduction starts from the foundation, and the double pointer method is widely used in basic problems. LeetCode 27, 977, 15 and 18 are the problems I have done in recent days, which can be well solved by double pointer method: 27: It is equivalent to dividing the array into two parts: the first part is the valid p ...

Generic, "generic" means broad, and "type" means data type. As the name suggests, a generic type is a type suitable for multiple data types. It is usually defined by Object. In theory, it can store any type of data. If we have studied arrays, we should know that the same data types are stored in arrays, such as integer and ...

1. Common methods of StringBuilder class The StringBuilder append (any type) parameter is appended to a string, and becomes a string no matter what the parameter is written It is equivalent to the + operation in the string public static void builderAppend(){ StringBuilder builder = new StringBuilder(); //The append method appends a st ...

1 distributed 1.1 what is distributed A distributed system must be a system composed of multiple nodes. Among them, nodes refer to computer servers, and these nodes are generally not isolated, but interconnected.Our nodes are deployed on these connected nodes, and their operations will be coordinated. For users, the distributed system is just ...

Find a beautiful machine and bury it. Case Automatic Regression 1, Background and purpose The total number of buried points on the line is more than 1000, and the main process case is more than 300. In the process of functional iteration, there are often statements about the regression of existing buried points. In the past, it used to consum ...

Construction steps Here, the database connection pool, springmvc, mybatis and service are created separately, and then import is integrated into ApplicationContext xml New projectGuide PackageCreate external file dB propertiesConfigure spring Dao xml: a. Associated database file b. Configure database source c. Configure bean sqlSessionFactory ...

Note: This article is a note taken following the mybatis course of crazy God talking about java. Don't spray it if you don't like it! Link to mybatis Video: [crazy God says Java] the latest complete tutorial of Mybatis, the IDEA version is easy to understand_ Beep beep beep_ bilibili What is MyBatis MyBatis is an excellent persistence la ...

brief introduction Ajax = asynchronous JavaScript and XML. AJAX is a technology that can update some web pages without reloading the whole web page. Ajax is not a new programming language, but a technology for creating better, faster and more interactive Web applications. In 2005, Google made AJAX popular through its Google suggest. Go ...

preface It mainly describes how to construct the maximum and minimum heap through priority queue to solve the topK problem. 1, Priority queue 1. The priority queue looks like a queue, and the bottom layer is implemented based on heap. 2. Priority queue can arrange the queued elements to their own positions according to the priority b ...