int a = new Random().nextInt(4);

swtich (Season.value()[a]){...}

中的[a]是什么用法和下方的case打印什么关系

这是为什么啊

老师请问为什么左边文件目录看不到我的项目文件夹，这是另一个文件夹，听课写代码的文件夹不是这个，怎么调出来呢？

就是这样按视频说的写的,注释里面写代码,但是取不到结果输出的是${a+b}

var adder =function (a,b) {
    return 'this num of the 2 numbers ${a+b}'
}

console.log(adder(5,3))

老师，Idea绑定的Maven中已经有setting配置文件，那这个路径中setting文件起作用嘛，我发现把它删了项目也不会报错啊。

老师 为啥我的工作目录换成e盘 创建文件就创建不了 d盘就可以

老师 请问这里的第五条_比较运算操作是什么呢?

onmouseleave和onmouseout有什么区别

#pip install python-pptx
from pptx import Presentation
def creat_ppt():
    #创建ppt对象
    ppt = Presentation()
    #添加幻灯片
    ppt.slides.add_slide(ppt.slide_layouts[0])
    #保存
    ppt.save('./creat_ppts/01_ppt.pptx')

if __name__ == '__main__':
    creat_ppt()

Traceback (most recent call last):

  File "D:\Users\W9020478\AppData\Local\Programs\Python\Python311\Lib\site-packages\pptx\compat\__init__.py", line 10, in <module>

    Container = collections.abc.Container

                ^^^^^^^^^^^^^^^

AttributeError: module 'collections' has no attribute 'abc'     

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

  File "f:\vscode\auto_ppt\01creat_ppt.py", line 2, in <module> 

    from pptx import Presentation

  File "D:\Users\W9020478\AppData\Local\Programs\Python\Python311\Lib\site-packages\pptx\__init__.py", line 14, in <module>     

    from pptx.api import Presentation  # noqa

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "D:\Users\W9020478\AppData\Local\Programs\Python\Python311\Lib\site-packages\pptx\api.py", line 15, in <module>

    from .package import Package

  File "D:\Users\W9020478\AppData\Local\Programs\Python\Python311\Lib\site-packages\pptx\package.py", line 6, in <module>

    from pptx.opc.package import OpcPackage

  File "D:\Users\W9020478\AppData\Local\Programs\Python\Python311\Lib\site-packages\pptx\opc\package.py", line 11, in <module>

    from pptx.compat import is_string, Mapping

  File "D:\Users\W9020478\AppData\Local\Programs\Python\Python311\Lib\site-packages\pptx\compat\__init__.py", line 14, in <module>

    Container = collections.Container

                ^^^^^^^^^^^^^^^^^^^^^

AttributeError: module 'collections' has no attribute 'Container'

这是什么错误

信息: Illegal access: this web application instance has been stopped already. Could not load []. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.

java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load []. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.

at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1305)

at org.apache.catalina.loader.WebappClassLoaderBase.getResource(WebappClassLoaderBase.java:986)

at com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.checkContextClassLoaders(AbandonedConnectionCleanupThread.java:96)

at com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:69)

at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135)

at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)

at java.base/java.lang.Thread.run(Thread.java:844)

浏览器显示无限循环重定向，不知道什么原因

老师这个地方的train_bottleneck，视频里说不对darknet53训练了，是什么意思？darknet53是一个配置文件 ，里边配置的是什么

老师，我将数据包导入以后，没有出现连接地址，出错了是什么情况？

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
null
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2260)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:787)
	at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:357)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
	at java.sql.DriverManager.getConnection(DriverManager.java:664)
	at java.sql.DriverManager.getConnection(DriverManager.java:247)
	at cn.sxt.dubtil111.DBUtil.getConnection(DBUtil.java:25)
	at cn.sxt.dubtil111.DBUtil.main(DBUtil.java:51)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:344)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2181)
	... 13 more
Caused by: java.net.ConnectException: Connection refused: connect
	at java.net.DualStackPlainSocketImpl.connect0(Native Method)
	at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
	at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at java.net.Socket.connect(Socket.java:538)
	at java.net.Socket.<init>(Socket.java:434)
	at java.net.Socket.<init>(Socket.java:244)
	at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:293)
	... 14 more

出现了以上错误！

这个怎么解决呀