HTTP Status 500 - An exception occurred processing JSP page /change.jsp at line

Question

各位大佬帮忙看看HTTP Status 500 - An exception occurred processing JSP page /change.jsp at line 24
type Exception reportmessage An exception occurred processing JSP page /change.jsp at line 24description The server encountered an internal error that prevented it from fulfilling this request.exception 
org.apache.jasper.JasperException: An exception occurred processing JSP page /change.jsp at line 2421: if ("changestudent".equals(request.getParameter("action")))
22: request.setAttribute("action", "adminmanger.jsp");
23: String name=request.getParameter("name");
24: name= new String(name.getBytes("ISO-8859-1"),"utf-8");
25: String sex=request.getParameter("sex");
26: sex= new String(sex.getBytes("ISO-8859-1"),"utf-8");
27: String tel=request.getParameter("tel");
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:575)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477)
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)root cause 
java.lang.NullPointerException
org.apache.jsp.change_jsp._jspService(change_jsp.java:105)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:439)
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)

Answer 1

24: name= new String(name.getBytes("ISO-8859-1"),"utf-8");
name为null....

Answer 2

楼主看看这里，java.lang.NullPointerException，空指针。说明你的name值为空，调用getbytes当然会报错了。debug检查一下name取值的地方有没有取到吧

Answer 3

HTTP Status 500 - An exception occurred processing JSP page /change.jsp at line 26
type Exception reportmessage An exception occurred processing JSP page /change.jsp at line 26description The server encountered an internal error that prevented it from fulfilling this request.exception 
org.apache.jasper.JasperException: An exception occurred processing JSP page /change.jsp at line 2623: String name=request.getParameter("name");
24: name= new String(name.getBytes("ISO-8859-1"),"utf-8");
25: String sex=request.getParameter("sex");
26: sex= new String(sex.getBytes("ISO-8859-1"),"utf-8");
27: String tel=request.getParameter("tel");
28: tel= new String(tel.getBytes("ISO-8859-1"),"utf-8");
29: String dormbulidname=request.getParameter("dormbulidname");