在正常注冊界面點擊提交之后就會出現這樣的錯誤是什么問題？

HTTP Status 500 - Unable to compile class for JSP:

type Exception report

message Unable to compile class for JSP:

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to compile class for JSP:

An error occurred at line: 28 in the jsp file: /out.jsp
Type mismatch: cannot convert from String[] to String
25: ? ? <h1>request鍐呯疆瀵硅薄</h1>
26: ? ? 鐢ㄦ埛鍚嶏細<%=request.getParameter("username") %><br>
27: ? ? 鐖卞ソ錛?<%
28: ? ? ? ? ? ? ? ? ?String favorites=request.getParameterValues("favorite");
29: ? ? ? ? ? ? ? ? ?for( int i=0;i<favorites.length();i++){
30: ? ? ? ? ? ? ? ? ?out.println(favorites[i]+" ? ? ?");
31: ? ? ? ? ? ? ? ? ?}


An error occurred at line: 30 in the jsp file: /out.jsp
The type of the expression must be an array type but it resolved to String
27: ? ? 鐖卞ソ錛?<%
28: ? ? ? ? ? ? ? ? ?String favorites=request.getParameterValues("favorite");
29: ? ? ? ? ? ? ? ? ?for( int i=0;i<favorites.length();i++){
30: ? ? ? ? ? ? ? ? ?out.println(favorites[i]+" ? ? ?");
31: ? ? ? ? ? ? ? ? ?}
32: ? ? ? ? ? ? ? ? ? %>
33: ? ? ? ? ? </body>


Stacktrace:
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:103)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:366)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:490)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:379)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:341)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:663)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:364)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.79 logs.

PS：視頻里的request.jsp我寫的是out.jsp，還有就是視頻下有一個scope.jsp? 這個是必須要有的嗎，求解答。