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1. Classes and objects Scala is a functional object-oriented language. It also supports the idea of object-oriented programming, and also has the concept of class and object. We can still develop object-oriented applications based on Scala. 1.1 related concepts What is object oriented? Object oriented is a programming idea, It is based on p ...

prefaceThis chapter introduces the extension of functions. Some knowledge that is not commonly used can be understood.Link to the original text of this chapter: Extension of function. Default values for function parametersES6 allows you to set default values for function parameters, that is, write them directly after the parameter definition.Wh ...

Time type The time.Time type represents time. We can obtain the current time object through the time.Now() function, and then obtain the information such as year, month, day, hour, minute and second of the time object. The example code is as follows: func main() { current := time.Now() fmt.Println(current) // 2021-11-26 16:13:54.3960877 +080 ...

2021SC@SDUSC catalogue Hash index In addition to using B-Tree index, postgreSQL can also use hash index. Hash index has faster query speed. This article mainly explains the principle of hash index, compares it with B-Tree, and analyzes the relevant data structure of hash index in the source code. Hash indexing principle Hash table The ...

Thoughts on cc3k village operation When I finished this assignment in object-oriented curriculum design, I haven't summarized my experience. Today, take the opportunity to answer the students' questions to summarize. Before starting The teacher asked to implement it in C + +, but on the other hand, I only knew this language at that time. At ...

About forEach synchronization and asynchrony Verify whether forEach is synchronous or asynchronous Some people have told me that forEeach is asynchronous ~ asynchronous code can't be put into execution ~ I was confused at that time, as if it wasn't the case when I first learned javascript Some people engraved a scar on you ~ tmd smiled and ...

Introduction:   MySQL is a relational database management system commonly used in Web site scenarios such as LAMP and LNMP. This article will show you how to install, configure, and remotely access MySQL databases on an ECS instance of the CentOS system. Mirror download, domain name resolution, time synchronization Click   Alibaba ...

1, Message prompt box and dialog box 1. Use Toast to display the message prompt box There are contacts before the message prompt box. The main application is Toast.makeText().show Next, learn in detail The objects of the Toast class have the following common methods setDuration(int duration) sets the duration toast.length of the message_ ...

1. Understanding of volatile? volatile is a lightweight synchronization mechanism provided by Java virtual machine Ensure visibilityProhibit instruction sortingAtomicity is not guaranteed JMM (Java memory model) JMM itself is an abstract concept, which does not really exist. It describes a set of regulations or specifications, which def ...

1. Concept of Java Io flow Stream: represents any data source object capable of producing data or receiving end object capable of receiving data. The essence of flow: data transmission. According to the characteristics of data transmission, the flow is abstracted into various types to facilitate more intuitive data operation. Function: ...