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Three characteristics of object-oriented: inheritance, encapsulation and polymorphism inherit Inheritance makes it easier to implement class extensions. For example, if we define a human, then we only need to extend the human to define the Boy class. The code reuse is realized, and don't need to rein ...

python learning notes (8) while loop 1. while cycle In the previous blog, we have learned about the for loop. Here we introduce another loop, while. The syntax of while is very simple. According to its English definition "when...", as long as the following conditional statements of while are ...

[eye] 1. A way to start Spring BootService startup class package com.npc.rest; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.ImportResource; /** * Frozen * 2020-1-29 */ /** * Previously, users used three annotations to ...

By analyzing these two usages, we can understand the concept of lock in java. One is instance lock (lock on an instance object, if the class is a single instance, then the lock also has the concept of global lock). The other is global lock (the lock is for a class, no matter how many objects are instance, then the thread shares the lock). The i ...

1. Error Instance Object When JavaScript parses or runs, the engine throws an error object whenever an error occurs.JavaScript natively provides the Error constructor, and all errors thrown are examples of this constructor. var err = new Error('Error'); console.log(err.message)； // "Error" ...

How to use the local version of the module in node.js. For example, in my application, I installed coffee script: npm install coffee-script This will install it in. / node \ u modules, while the coffee command is in. / node \ u modules /. Bin / coffee. Can I run this command when I am in the project's home folder? I guess I'm looking for ...

Install RestFramework $ pip install djangorestframework # settings.py INSTALLED_APPS = ( ... 'rest_framework', ) Create Serializer class from rest_framework import serializers from .models import Book, Author, Publisher class AuthorSerializer(serializers.Serializer): id = serializers.IntegerFie ...

This article is for reference only:Bili Bili video capture The video capture of station b is still relatively difficult. Compared with the video capture of other websites, it is also relatively difficult because of my curiosity and fear of death. I intend to analyze and analyze the video of station b. t ...

The original idea of doing this tutorial is: Although plt.plot(x,y) is a simple and convenient way, there are many detailed requirements for drawing tutorials involving academic paper, which need to further fine tune the pictures, and at this time, it needs to constantly Baidu Baidu, not to mention writ ...

This may happen during the development of foreground functions: For a list of multiple order commodities, click view details, which contains the countdown of the corresponding commodity activity time. If you click view instead of refreshing the entire page, you need to close the countdown when you view the details and return t ...