I am not able to find what is wrong with my webApp. This is my first project and i'm kinda stuck. All i know is that something is going wrong in ShoppingCart.java whenever i click add to cart in index.html it gives me a error code of series 500 i tried to look into console but didn't understand it fully. It is very simple code please tell me if you see something..
index.html
<table border="1px">
<th>PIZZA NAME</th> <th>PRICE</th> <th>ADD TO CART</th>
<form action="addToCart">
<tr>
<td> Peppereno</td>
<td> 20$ </td>
<td align="center">
<input type="hidden" name="name" value="peppereno"/>
<input type="hidden" name="price" value="20"/>
<input type="submit" value="Add to Cart"/>
</td>
</tr>
</form>
<form action="addToCart">
<tr>
<td> Barbeque</td>
<td> 10$</td>
<td align="center">
<input type="hidden" name="name" value="barbeque">
<input type="hidden" name="price" value="10"/>
<input type="submit" value="Add to Cart" />
</td>
</tr>
</form>
<form action="addToCart">
<tr>
<td> Farmhouse</td>
<td> 35$ </td>
<td align="center">
<input type="hidden" name="name" value="farmhouse"/>
<input type="hidden" name="price" value="35"/>
<input type="submit" value="Add to Cart"/>
</td>
</form>
</table>
Cart.java
package com.cart;
import java.util.HashMap;
public class Cart {
HashMap<String, Integer> cartItems;
public Cart() {
cartItems = new HashMap<>();
}
public HashMap<String, Integer> getItems() {
return cartItems;
}
public void addToCart(String item, Integer price) {
cartItems.put(item, price);
}
public void deleteFromCart(String item) {
cartItems.remove(item);
}
}
ShoppingCart.java
package com.cartServlet;
import com.cart.*;
@WebServlet("/ShoppingCart")
public class ShoppingCart extends HttpServlet {
private static final long serialVersionUID = 1L;
public ShoppingCart() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
HttpSession session = request.getSession();
Cart shoppingCart = (Cart) session.getAttribute("cart");
if (shoppingCart == null) {
shoppingCart = new Cart();
session.setAttribute("cart", shoppingCart);
}
String name = request.getParameter("name");
Integer price = Integer.parseInt(request.getParameter("price"));
shoppingCart.addToCart(name, price);
session.setAttribute("cart", shoppingCart);
RequestDispatcher dispatch = request.getRequestDispatcher("response.html");
dispatch.include(request, response);
HashMap<String, Integer> items = shoppingCart.getItems();
PrintWriter out = response.getWriter();
out.println("<table border='1px'>");
for (String key : items.keySet()) {
out.println("<tr><td>" + key + " - </td><td>" + "$" + items.get(key) + "</td></tr>");
}
out.println("</table>");
}
}
response.html
<h3>Pizza successfully added to the cart</h3>
<form action="index.html">
Add more pizza to cart<input type ="submit" value="go"/>
</form>
<h2>Cart</h2>
web.xml
<servlet>
<servlet-name>abc</servlet-name>
<servlet-class>com.cartServlet.ShoppingCart</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>abc</servlet-name>
<url-pattern>/addToCart</url-pattern>
</servlet-mapping>
logFile
Mar 30, 2016 7:42:26 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [abc] in context with path [/ShoppingCart] threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:679)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:213)
at com.cartServlet.ServletCart.doGet(ServletCart.java:46)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
