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关键字final 分别修饰一个类,一个方法,一个变量,各起什么作用

关键字final分别修饰一个类,一个方法,一个变量,各起什么作用 解答:final修饰类是不能被继承 fianl修饰方法不能在子类中被覆盖 final修饰变量,称为常量,初始化以后不能改变值。...

Call to undefined function thinkfinfo_open() 报错 解决方法

经过各方面排查,是fileinfo扩展没有安装安装即可...

js数组完美去重,区分undefined,NaN,null,字符串等

functionarray_unique(arr){letlen=arr.length;if(!len){return[];}lettmp=[];for(leti=0;i<len;i++){if(tmp.findIndex((v)=>{returnJSON.stringify(v)===JSON.strin...

pycharm python @符号不能识别 NameError: name 'app' is not defined

pycharmpython@符号不能识别NameError:name'app'isnotdefined解决办法:缺少:app=Flask(__name__)#导入Flask类fromflaskimportFlask#实例化,可视为固定格式app=Flask(__name__)#route()方法用于设定路由;类似spr...

解决 cannot find reference 'LSHForest' in '__init__.py'

 fromsklearn.neighborsimportLSHForest cannotfindreference'LSHForest'in'__init__.py'报错pip3list#查看sklearn版本号,我的是0.21,这个版本太高了可能改名字了或者其他原因sudopip3uninstall&nbs...

No result defined for action

在开发中总遇到这个问题,Noresultdefinedforaction:原因:Action中的属性值为空的时候,Struts2的默认拦截器会报错,但是又找不到input的Result,不能够把错误返回,所以报这种错误。解决方法:1.在页面中给空值赋默认值。2.重新定义一个Action,去掉空值的成员变量。3.添加in...

mysql 1449 : The user specified as a definer ('root'@'%') does not exist 解决方法

权限问题,授权给root 所有sql权限mysql>grantallprivilegeson*.*toroot@"%"identifiedby".";QueryOK,0rowsaffected(0.00sec)mysql>flushprivileges;QueryOK,0rowsaffected(...

Error: Cannot find module ‘webpack-cli/bin/config-yargs‘

/今配置一个webpack-dev-server进行服务端渲染时老是不正确npmrundev就崩了起初的配置为"devDependencies":{"webpack":"^5.1.3""webpack-dev-server":"^3.11.0"} 查了些资料都说是webpack3.x的版本与webpack-d...

TypeError: Cannot read property ‘make‘ of undefined

/这搞个html-webpack-plugin插件进来运行就一大篇报错尴尬看了一圈又是版本兼容的问题,做下修改。。。。OK运行成功...

props传值遇Cannot read property getAttribute of undefined异常

/今有一个echarts图标的子组件使用watch监听接受父组件传入的data,而在父组件页面再次根据日期筛选数据,重新传入子组件进行图表重绘时老实会提示报错vue.runtime.esm.js?6e6d:619[Vuewarn]:Errorincallbackforwatcher"chartData":"TypeEr...

Define class with itself as generic implementation. Why/how does this work?

https://stackoverflow.com/questions/10709061/define-class-with-itself-as-generic-implementation-why-how-does-this-work问题:I'venormallybeencreatingPrismEventsused...
代码星球 ·2021-02-08

File.Copy的时候Could not find a part of the path

https://developercommunity.visualstudio.com/content/problem/378265/filecopy-did-not-throw-the-correct-exception.htmlpathtoolong...

unable to find valid certification path to requested target

https://blog.csdn.net/write_down/article/details/791145731.知识预备要理解本文,需要掌握以下知识:https基本原理,包括证书分发和密钥协商等[1];http代理和https代理的基本原理[2];常用的本地http代理工具,如Fiddler,BurpSuite;...

501. Find Mode in Binary Search Tree

Givenabinarysearchtree(BST)withduplicates,findallthe mode(s) (themostfrequentlyoccurredelement)inthegivenBST.AssumeaBSTisdefinedasfollows:Theleftsubtr...
代码星球 ·2021-02-08
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