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From August Detlefsen <augustd...@yahoo.com>
Subject Re: NullPointerException when using JDBC ResultSet next() method
Date Mon, 08 Apr 2002 19:19:01 GMT
The stack trace says that your NullPointer occurs on line 45, but line
45 is blank. Is there some more code that you didn't ost? Import
statements, perhaps? 

I think it probably happened here: 

stmt = con.createStatement();

-IE: You were not able to get a Connection, con is null and calling its
methods will give you the NullPointer. Are you sure the driver loaded
properly?


--- "Philip Kazmier, CEM R&D" <philip.kazmier@nice.com> wrote:
> 
> 
> I am getting this error in a servlet compiled on Win2K, using
> JDK1.3.1 and
> Tomcat 3.3 with MySQL 3.23.47:
> 
> Location: /PSSoftware/servlet/ListAllOpenBugs
> Internal Servlet Error:
> java.lang.NullPointerException
> 	at ListAllOpenBugs.doGet(ListAllOpenBugs.java:45)
> 	at javax.servlet.http.HttpServlet.service(HttpServlet.java)
> 	at javax.servlet.http.HttpServlet.service(HttpServlet.java)
> 	at org.apache.tomcat.facade.ServletHandler.doService(Unknown Source)
> 	at org.apache.tomcat.core.Handler.invoke(Unknown Source)
> 	at org.apache.tomcat.core.Handler.service(Unknown Source)
> 	at org.apache.tomcat.facade.ServletHandler.service(Unknown Source)
> 	at org.apache.tomcat.core.ContextManager.internalService(Unknown
> Source)
> 	at org.apache.tomcat.core.ContextManager.service(Unknown Source)
> 	at
>
org.apache.tomcat.modules.server.Http10Interceptor.processConnection(Unknown
> Source)
> 	at org.apache.tomcat.util.net.TcpWorkerThread.runIt(Unknown Source)
> 	at
> org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(Unknown
> Source)
> 	at java.lang.Thread.run(Thread.java:484)
> 
> 
> Here is the servlet code:
> 
> public class MySQLTest extends HttpServlet
> {
> 	public void doGet(HttpServletRequest req, HttpServletResponse res)
> throws ServletException, IOException
> 	{
> 		Connection con = null;
> 		Statement stmt = null;
> 		ResultSet rs = null;
> 
> 		res.setContentType("text/html");
> 		PrintWriter out = res.getWriter();
> 
> 		try
> 		{
> 			// Load the MySQL driver
> 			Class.forName("org.gjt.mm.mysql.Driver");
> 			//try {
> 	
> //Class.forName("twz1.jdbc.mysql.jdbcMysqlDriver");
> 			//}
> 			//catch(Exception e){out.println(e);}
> 
> 			// Get a connection to the database
> 			con =
>
DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&pass
> word=typhoon");
> 	
> 			// Create a statement object
> 			stmt = con.createStatement();
> 
> 			// Execute and SQL query, get a result set
> 			rs = stmt.executeQuery("SELECT * from test");
> 
> 			// Display the result set as a list
> 	
> out.println("<HTML><HEAD><TITLE>Test</TITLE></HEAD>");
> 			out.println("<BODY>");
> 			out.println("<UL>");
> 			while(rs.next()) 
> 			{
> 				out.println("<LI>" + rs.getString("test"));
> 			}
> 			out.println("</UL>");
> 			out.println("</BODY></HTML>");
> 
> 		}
> 		catch (ClassNotFoundException e)
> 		{
> 			out.println("Couldn't load the database driver-> " +
> e.getMessage());
> 		}
> 		catch(SQLException e)
> 		{
> 			out.println("SQLException caught: " +
> e.getMessage());
> 		}
> 
> 		finally
> 		{
> 			try
> 			{
> 				if (con != null) con.close();
> 			}
> 			catch(SQLException ignored) { }
> 		}
> 	}
> };
> 
> As you can see I tried this with Oracle.  I get the same result when
> I used
> Oracle.
> 
> Thanks.
> 
> Phil Kazmier
> Developer,  CEM
> NICE Systems
> Denver, Colorado
> Office (720) 264-4284
> 
> 
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