Java遇到的问题

问题1：

The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path

JSP页面顶端出现红色的报错信息：The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path。原来Javaweb工程类中没有添加Tomcat运行时相关类导致。
下面是具体的解决方法：
1、右击web工程-》属性或Build Path-》Java Build Path->Libraries-> Add Libray...->Server Runtime -》Tomcat Server
2、切换到Java Build Path界面中的Orader and Export，选择Tomcat。

注意：
按以上方法操作时，若打开Server Runtime后一片空白，需要设置Apache服务器。设置方法为：window->Preferences->Server->Runtime Environment -> add --> 选择Apache的版本后点Next，再填入你apache服务器软件的安装（解压后）地址。

转自https://blog.csdn.net/qq_37844454/article/details/83387989的答案。

问题二：

Multiple annotations found at this line:

String cannot be resolved to a type

No exception of type ServletException can be thrown; an exception type must be a subclass of 
Throwable

The method getContextPath() from the type HttpServletRequest refers to the missing type String

java.io.IOException cannot be resolved to a type

解决方法：build path 中重新选择server runtime ，jre

问题3：

Description	Resource	Path	Location	Type
Target runtime Apache Tomcat v7.0 is not defined.	JavaEE_2_SpringMVC_1.1		Unknown	Faceted Project Problem

解决方法：

Eclipse导入工程后工程上显示一个小红叉，但工程里没有文件错误，也没有语法错误，在problems中显示错误是：Target runtime Apache Tomcat 6.0 is not defined.

【项目】->【右键】->【Properties】.

Target runtimes -----> 重新选择tomcat

转自https://blog.csdn.net/u012838836/article/details/53290540的blog。

数组访问越界
Java.lang.ArrayIndexOutofBoundException