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Reprint: https://segmentfault.com/a/1190000022521844 0. Preface Hello, I'm brother! This is my 221 high-quality original articles. If you need to reprint, please indicate the address at the beginning of the text, crab! This article has been included in my 75K Star Java open source project JavaGuide: https://github.com/Snailclimb/JavaGuide ...

Inter thread synchronization Locking mechanism: mutex, conditional variable, semaphore, read / write lockMutex: provides a way for data structures to be modified concurrently in an exclusive mannerRead / write lock: write lock preempts resources first. Read lock allows multiple threads to read shared data together, and write lock operation ...

Inner class and API, exception Inner class Access characteristics of internal classes Internal classes can directly access members of external classes, including private classes An object must be created for an external class to access members of an internal classThe definition location of the class inside the member In a class, a method is ...

java Servlet annotation implementation filter What I wrote earlier: This article is related to Token verification. Visitors can go and have a look at my article Implementation of Token of Servlet How to implement Servlet filter: 1. Configure in xml file 2. Add comments in the file header First, we should know what a filter is ...

Go Error's design philosophy is "Errors Are Values". How should this sentence be understood? It's difficult to translate. However, from the perspective of source code, it seems easier to understand the meaning behind it. The source code of Go Error is very simple, just a few lines: // src/builtin/builtin.go type error interface { ...

preface Three basic characteristics of object-oriented: encapsulation, inheritance and polymorphism. For more detailed concepts, see the blogger's article Three characteristics and five basic principles Tip: the following is the main content of this article. The following cases can be used for reference 1, Encapsulate field 1. Conce ...

1 CSS Web page -- > people HTML -- > skeleton CSS -- > skin and flesh CSS refers to cascading style sheets (cascading style sheets), which are mainly used to set the text content (font, size, alignment, etc.) in HTML pages, the appearance of pictures (width and height, border style, margin, etc.) and the layout of layout, etc. CSS is ...

1.1 define integer / long integer / single precision floating point... Variables int variable name = initial value; eg: int num = 10;//Define an integer variable System.out.println(num);//Output defined integer variables public class HelloWorld { public static void main (String [] args) { int a=10;//Defines a variable of type int System.o ...

Prepare dataset 1. Shooting Use the iphone 7 Plus continuous shooting function to take 1000 pictures of left and right hands in different light. 2. Picture renaming Mobile phone automatic naming is inconvenient to traverse, so it needs to be changed to 1 jpg，2.jpg. Run the following code. import os import re import sys path = r"D:data\im ...

For association methods, the system provides 9 schemes, as follows: In the above example, we use the one-to-one association model, which also has relative reverse association; An example is given below: class Profile extends Model { public function user() { return $this->belongsTo(User::class); } } $profile = ProfileModel ...