Programmer Think

1, Collection introduction 1) Scala's collections fall into three categories: sequence Seq, Set and Map. All collections are extended from Iterable Characteristics. 2) For almost all collection classes, Scala provides both variable and immutable versions, which are located in the following two places: Package Immutable set: ...

Uploading files should be the most frequently encountered scenario. Today, let's simply do a Spring Boot file uploading function with you. Without much nonsense, let's start directly.The project structure is as follows:pom dependency<dependencies> <dependency> <groupId>org.springframework.boot</groupId> ...

1.UDP broadcast. The client opens a port to listen to data. The server specifies the port to send data, and the client can receive the data. The broadcast address bound by the server is 255.255.255.255 Client listening: public class BroadcastClient { private int MessageIndex = 0; private int port = 6787;//Data listening binding port ...

Java notes Java data type - basic type Character type Char Character type, which takes up 2 bytes. Only a single character is allowed. Character quotation marks are forced to use single quotation marks char a = 'a'; Forced digital conversion of Char Use Char to cast numbers to output Unicode values of corresponding characters ...

13.MyBatis caching mechanism 1. Why cache? When users frequently query some fixed data, they query these data from the database for the first time and save them in the cache. When users query these data again, they do not need to query through the database, but query in the cache. Reduce the loss caused by network connection and database quer ...

Multithreading advanced Six states of threads in virtual machine New status (NEW) -- create thread objectReady state (runnable) -- start methodBlocked ------------- unable to get lock objectWaiting -- waiting methodTimed_waiting -- sleep methodTerminated -------------- all codes have been run Thread pool code implementation Create a poo ...

Josephu Joseph Ring – the leading out of one-way ring linked list Josephu's problem is: let n people with numbers 1, 2,... N sit around. It is agreed that the person with number k (1 < = k < = n) will count from 1, and the person who counts to m will be listed. Its next person will count from 1, and the person who counts to m will ...

1, @ ModelAttribute usage Bind request parameters to command object (input parameter object): when placed on the input parameter of the controller method, it is used to bind multiple request parameters to a command object, so as to simplify the binding process, and is automatically exposed as model data for use in view page display; When t ...

Bitmap addition and subtraction multiplication and division Let's briefly explain what our bitmap is First of all, we can't avoid storing data in many cases during data processing. At this time, we will open up memory to create arrays to store our data But let's take shaping as an example. int takes up 4 bytes of space, Suppose I want t ...

preface I believe that this article is not the first time for my classmates to see articles about HashMap. Most of the online HashMap articles are not suitable for me, so I decided to understand the source code from scratch. I will use the relatively simple logic to convince myself to understand the source code. If you are interested, please l ...