[FIXED] Why is my Servlet only displaying a blank page, and not updating database?

Issue

I have made a web app using Eclipse. I've created an HTML form that will use to sign up, and get user details to store in the database (MySQL Workbench 6.3) but after signing up the servlet shows a blank page. What am I doing wrong?

This is my form:

<form  name="signup" method="post" action="SignUpServlet">
    
    <table id="myTable" >
        <caption><h3>SIGN UP</h3></caption>
        <hr>
        <p text align="center">Please Fill The Below Form To Sign Up</p>
        <tr>
            <td>First Name</td>
            <td><input type="text" placeholder="Enter First Name" name="Fname"  id="Fname" required/></td>                      

        </tr>

        <tr>
            <td>Last Name</td>
            <td><input type="text" placeholder="Enter Last Name" name="Lname" id="Lname" required/></td>                        

        </tr>

        <tr>
            <td>E-Mail</td>
            <td><input type="email" placeholder="Enter Email" name="Email" id="Email" required/></td>                       

        </tr>

        <tr>
            <td>User Name</td>
            <td><input type="text" placeholder="User Name" name="Uname" id="Uname" required/></td>                      

        </tr>

        <tr>
            <td>Enter Password</td>
            <td><input type="password" placeholder="Enter Password" name="Password" id="password" onkeyup='check();' required/></td>                        

        </tr>

        <tr>
            <td>Re-Enter Password To Confirm</td>
            <td><input type="password" placeholder="Re-Enter Password" name="repassword" id="repassword" onkeyup='check();' required/>
            <span id='message'></span></td>
        </tr>
        
        <tr>
            <td>Mobile Number <i>: Optional</i></td>
            <td><input type="tel" placeholder="Mobile Number" name="Mnumber" id="mnumber"/></td>

        <tr>
        <tr>
            <td>Home Address <i>: Optional</i></td>
            <td><input type="text" placeholder="Home Address" name="Haddress" id="haddress"/></td>
        </tr>
            <td><input type="checkbox" checked="checked" name="remember" style="margin-bottom:15px"> Remember me
            <td><p>By creating an account you agree to our <a href="#" style="color:white">Terms & Policies</a>.</p>
        </tr>
        <tr>            
   <td><button type="button" onclick="document.getElementById('myTable').style.display='none'" class="cancelbtn">Cancel</button></td>
   <td><input type="submit" class="signupbtn" value="Sign Up"></td>
   

        </tr>
    </table>


</form>

This is the servlet:

package jdbc;

import java.sql.*;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class SignUpServlet
 */
@WebServlet("/SignUpServlet")
public class SignUpServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
   
/**
 * @see HttpServlet#HttpServlet()
 */
public SignUpServlet() {
    
    super();
    // TODO Auto-generated constructor stub
}

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.getWriter().println("Hellotest");
    // TODO Auto-generated method stub
    response.getWriter().append("Served at: ").append(request.getContextPath());
}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("testing123");

    try {
        String Fname =request.getParameter("Fname");
        String Lname =request.getParameter("Lname");
        String Email =request.getParameter("Email");
        String Uname =request.getParameter("Uname");
        String Password =request.getParameter("Password");
        String Mnumber=request.getParameter("Mnumber");
        String Haddress =request.getParameter("Haddress");
        
        
        String sql ="insert into sign-up(Fname,Lname,Email,Uname,Password,Mnumber,Haddress) values(?,?,?,?,?,?,?)";
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/vs&fsms","root","root");
        
        PreparedStatement ps = conn.prepareStatement(sql);
        
        ps.setString(1, Fname);
        ps.setString(2, Lname);
        ps.setString(3, Email);
        ps.setString(4, Uname);
        ps.setString(5, Password);
        ps.setString(6, Mnumber);
        ps.setString(7, Haddress);
        
        
        
        ps.executeUpdate();
        PrintWriter out= response.getWriter();
        
        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/Signin.jsp");
        dispatcher.forward(request, response);
        
        
    } catch (ClassNotFoundException | SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

PS: SQL Schema name is vs&fsms, table name is sign-up.

Solution

What error are you seeing in your IDE? Just by looking at your code i can say that you will have a problem with your table name. You can't have a dash/hyphen symbol (-) in table names unless you enclose it with back-ticks (`). So what is happening is you are invoking the catch exception block:

   } catch (ClassNotFoundException | SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

And therefore your forward to jsp never runs:

RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/Signin.jsp");
dispatcher.forward(request, response);

Move the RequestDispatcher outside the try/catch block and then fix your table name and it should work fine.

Or enclose your table name in backticks:

    String sql ="insert into `sign-up` (Fname,Lname,Email,Uname,Password,Mnumber,Haddress) values(?,?,?,?,?,?,?)";

Answered By - Jonathan Laliberte
Answer Checked By - Candace Johnson (JavaFixing Volunteer)