JSP error at line 31

1
votes

When i am running the jsp page drops me this error , any suggestion in order to fix it , (i know jsp with java its not good)...

type Exception report

message An exception occurred processing JSP page /assets/jsp/create-dest-code.jsp at line 31

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

exception org.apache.jasper.JasperException: An exception occurred processing JSP page /assets/jsp/create-dest-code.jsp at line 31

28: if(id > -1) 29: { 30: int insert_ch; 31: for(int i=0;i insert_ch=myStatement.executeUpdate("INSERT INTO Dest_has_Categories (Dest_idDest,Categories_idCategories) VALUES ('"+id+"','"+cat[i]+"')"); 34: }

Stacktrace: org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:574) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340) javax.servlet.http.HttpServlet.service(HttpServlet.java:729) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

root cause java.lang.NullPointerException org.apache.jsp.assets.jsp.create_002ddest_002dcode_jsp._jspService(create_002ddest_002dcode_jsp.java:136) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) javax.servlet.http.HttpServlet.service(HttpServlet.java:729) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340) javax.servlet.http.HttpServlet.service(HttpServlet.java:729) 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/8.0.33 logs.

my code : 

<%
String id8=request.getParameter("id8"); //Country field  
String id9=request.getParameter("id9"); //City field
String id10=request.getParameter("id10"); //URL field
int id = -1;

Class.forName("com.mysql.jdbc.Driver"); 
String myDatabase = "jdbc:mysql://localhost:3306/project_app?user=root&password=1234"; 
Connection myConnection = DriverManager.getConnection(myDatabase);
Statement myStatement = myConnection.createStatement();  

String sqlInsert = "INSERT INTO dest(Country,City,URL) VALUES ('"+id8+"', '"+id9+"','"+id10+"')";
myStatement.executeUpdate(sqlInsert);
ResultSet rs = myStatement.executeQuery("SELECT idDest FROM dest WHERE Country='"+id8+"' AND City='"+id9+"' AND URL='"+id10+"'" );
while (rs.next()) {
    id=rs.getInt(1);
}
String cat[]=request.getParameterValues("dest1");

if(id > -1)
{
    int insert_ch;
    for(int i=0;i<cat.length;i++)
    {
      insert_ch=myStatement.executeUpdate("INSERT INTO Dest_has_Categories (Dest_idDest,Categories_idCategories) VALUES ('"+id+"','"+cat[i]+"')");
    }
}


 myStatement.close(); 
   myConnection.close(); %>

   <h1 style="color:blue;">Successful Registration </h1>
2
javasqlapachejsp

2 Answers

1
votes

I assume that once you know what is the line #31, you will be able to fix your NPE thanks to many other questions of this type so let's focus on how to find the line #31 in your case.

According to your stacktrace you are using Tomcat 8, so the source code of your jsp file /assets/jsp/create-dest-code.jsp is in $TOMCAT_HOME/work/Catalina/localhost/assets/org/apache/jsp/jsp/create-dest-code_jsp.java, from here check the line #31 and you will know how to fix it.

Actually you have already the answer here:

28: if(id > -1) 29: { 30: int insert_ch; 31: for(int i=0;i insert_ch=myStatement.executeUpdate("INSERT INTO Dest_has_Categories (Dest_idDest,Categories_idCategories) VALUES ('"+id+"','"+cat[i]+"')"); 34: }

It seems that your variable cat is null which probably means that you have no value for the parameter dest1.

0
votes

Are you sure you connection string is valid? In the example here There is more details in the connection string that is missing in your code (like database name) : 

Connection con = null;
    try {

      con = DriverManager.getConnection(
          "jdbc:sqlserver://localhost\\SQLEXPRESS;"
        + "user=sa;password=HerongY@ng;"
        + "database=AdventureWorks2014");

source