prepared statement

[rakhi sinha]

i am using following code but if condition is not working .....values are coming from previous servlet if i dont enter any value for i2 and i3 then the value of m2 and m3 will be null but statements in second and third if condition are being executed...please help me to solve this problem

public class Data2 extends HttpServlet {   
  
  public void doGet(HttpServletRequest req, HttpServletResponse res)   
                               throws ServletException, IOException {   
    Connection con = null;   
    String userName = "";   
    String password = "";   
    String url = "";      
    res.setContentType("text/html");   
    String a = req.getParameter("no");//no     
    String k=req.getParameter("radiobutton1");//item type   
    String m1 = req.getParameter("i1");// item1   
    String n1 = req.getParameter("q1");//quantity1   
    String o1 = req.getParameter("c1"); //price1   
    String m2 = req.getParameter("i2");// item2   
    String n2 = req.getParameter("q2");//quantity2   
    String o2 = req.getParameter("c2"); //price2   
    String m3 = req.getParameter("i3");// item3   
    String n3 = req.getParameter("q3");//quantity3   
    String o3 = req.getParameter("c3"); //price3    
    String q = req.getParameter("prev_ref");//pre ref   
    PrintWriter out = res.getWriter();   
    HttpSession session  = req.getSession();   
    String s = a;   
    session.setAttribute("no",s);   
    try {   
     Class.forName ("oracle.jdbc.driver.OracleDriver");   
     con= DriverManager.getConnection (url, userName, password);   
     if(m1!=null)   
     {   
     PreparedStatement pst = con.prepareStatement("INSERT into pr1 VALUES(?,?,?,?,?)");    
     pst.setString(1,k);     
     pst.setString(2,m1);    
     pst.setString(3,n1);     
     pst.setString(4,o1);    
     pst.setString(5,a);    
     pst.executeUpdate();   
     pst.close();   
     }   
     if(m2!=null)   
     {    
     PreparedStatement pst1 = con.prepareStatement("INSERT into pr1 VALUES(?,?,?,?,?)");    
     pst1.setString(1,k);     
     pst1.setString(2,m2);    
     pst1.setString(3,n2);     
     pst1.setString(4,o2);    
     pst1.setString(5,a);     
     pst1.executeUpdate();   
     pst1.close();   
     }   
     if(m3!=null)   
     {   
     PreparedStatement pst2 = con.prepareStatement("INSERT into pr1 VALUES(?,?,?,?,?)");    
     pst2.setString(1,k);     
     pst2.setString(2,m3);    
     pst2.setString(3,n3);     
     pst2.setString(4,o3);    
     pst2.setString(5,a);     
     pst2.executeUpdate();   
     pst2.close();   
     }   
        }   
    catch(ClassNotFoundException e1) {    
      out.println("Couldn't load database driver: " + e1.getMessage());   
    }   
    catch(SQLException e1) {    
      out.println("SQLException caught: " + e1.getMessage());   
    }   
    finally {   
          try {   
        if (con != null) con.close();   
      }   
      catch (SQLException ignored) { }   
    }   
  }   
}  

[Tim Moores]

Most likely m2 and m3 are NOT null; their value is probably the zero-length string.

[rakhi sinha]

Tim Moores wrote:Most likely m2 and m3 are NOT null; their value is probably the zero-length string.

but when i try to print thees values .null value is printed so what should i do for this ....i dont want to print all the three if condition .depends on values of i1,i2 and i3 entered from previous servlet

[Tim Moores]

That sounds unlikely. We don't know how you print the values, but if the value of m1 is null, then a block guarded by "if (m1!=null)" wouldn't be executed.

Your variable names are very confusing, by the way - m1, n1, o1 means nothing. Why aren't they named i1, q1, c1 to go along with the parameter names? Or, even better, have a name that actually describes what they contain?

There's no point in loading the DB driver every single time the servlet is accessed, by the way. You should move that code to the init method.

[rakhi sinha]

Tim Moores wrote:That sounds unlikely. We don't know how you print the values, but if the value of m1 is null, then a block guarded by "if (m1!=null)" wouldn't be executed.

Your variable names are very confusing, by the way - m1, n1, o1 means nothing. Why aren't they named i1, q1, c1 to go along with the parameter names? Or, even better, have a name that actually describes what they contain?

There's no point in loading the DB driver every single time the servlet is accessed, by the way. You should move that code to the init method.

i will chage variable name .but i think it is not releted to my problem ...i am printing the value of m2 amd m3 in next page by redirecting the servlet to next page only for checking their values....i am confused that where am i wrong ???

[Eshwin Sukhdeve]

try with this StringUtils class.

if(!StringUtils.isEmpty(s1))
{

}

if s1 is null or empty String.it will work.

[Wendy Gibbons]

rakhi sinha wrote:

Tim Moores wrote:That sounds unlikely. We don't know how you print the values, but if the value of m1 is null, then a block guarded by "if (m1!=null)" wouldn't be executed.

Your variable names are very confusing, by the way - m1, n1, o1 means nothing. Why aren't they named i1, q1, c1 to go along with the parameter names? Or, even better, have a name that actually describes what they contain?

There's no point in loading the DB driver every single time the servlet is accessed, by the way. You should move that code to the init method.

i will chage variable name .but i think it is not releted to my problem ...i am printing the value of m2 amd m3 in next page by redirecting the servlet to next page only for checking their values....i am confused that where am i wrong ???

changing the names will not solve your problem... but it will mean that it is easier to read your code and understand it, and when you have to come back to maintain this code later you will understand what it is doing.

[Wendy Gibbons]

rakhi sinha wrote:

Tim Moores wrote:Most likely m2 and m3 are NOT null; their value is probably the zero-length string.

but when i try to print thees values .null value is printed so what should i do for this ....i dont want to print all the three if condition .depends on values of i1,i2 and i3 entered from previous servlet

do they actually contain the word 'NULL'?

[Tim Moores]

rakhi sinha wrote:i am printing the value of m2 amd m3 in next page by redirecting the servlet to next page only for checking their values

If you do a redirect then all your parameters will be gone, so that's not a valid test. You might want to consider using a debugger to step through the actual code that causes the problem.