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POException while running GWT application
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  1. POException while running GWT application
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    copied!<p>I have built my first GWT app. giving no compilation errors neither run-time errors. However, when the application is loaded into the browser (using Interner Explorer) and I enter <strong>username</strong> and <strong>password</strong> field to validate the user, it throws exceptions. Using GWT-RPC method, entire code and interfaces are provided. I'm using <strong>HSQL</strong> for database connection(back end).</p> <p>------------------CODE (CLIENT)</p> <pre><code>package com.vin.client; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.rpc.AsyncCallback; import com.google.gwt.user.client.ui.Button; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.PasswordTextBox; import com.google.gwt.user.client.ui.RootPanel; import com.google.gwt.user.client.ui.TextBox; public class HelloWorld implements EntryPoint{ private UserServiceAsync UserService = (UserServiceAsync) GWT.create(UserService.class); public void onModuleLoad() { Button click=new Button("Click Here"); Label name=new Label("Enter Name"); Label passwrd=new Label("Enter Password"); final TextBox t_name=new TextBox(); final PasswordTextBox t_passwrd=new PasswordTextBox(); click.addClickHandler(new ClickHandler() { public void onClick(ClickEvent ev) { String temp_user=t_name.getText(); String temp_pass=t_passwrd.getText(); UserService.loginuser(temp_user, temp_pass, new AsyncCallback&lt;String&gt;() { public void onFailure(Throwable caught) { Window.alert("Please enter valid details"); } public void onSuccess(String result) { Window.alert("Welcome"); // Window.open("http://127.0.0.1:8888/ExWid.html?gwt.codesvr=127.0.0.1:9997", "Dem", null); } }); } }); RootPanel.get().add(name); RootPanel.get().add(t_name); RootPanel.get().add(passwrd); RootPanel.get().add(t_passwrd); RootPanel.get().add(click); } } </code></pre> <p>-----------------------------CLIENT INTERFACE (1)</p> <pre><code>package com.vin.client; import com.google.gwt.user.client.rpc.RemoteService; public interface UserService extends RemoteService { public String loginuser(String username, String password); } </code></pre> <p>----------------------------CLIENT ASYNC INTERFACE</p> <pre><code>package com.vin.client; import com.google.gwt.user.client.rpc.AsyncCallback; public interface UserServiceAsync { public void loginuser(String username, String password, AsyncCallback&lt;String&gt; callback); } </code></pre> <p>--------------------------IMPLEMENTATION OF CLIENT USERSERVICE (SERVER)...DATABASE CONNECTION</p> <pre><code>package com.vin.server; import java.sql.DriverManager; import java.sql.ResultSet; import com.google.gwt.dev.generator.ast.Statement; import com.google.gwt.user.client.Window; import com.google.gwt.user.server.rpc.RemoteServiceServlet; import com.vin.client.UserService; public class UserServiceImpl extends RemoteServiceServlet implements UserService{ private static final long serialVersionUID = 1L; public String loginuser(String username,String password) { try { java.sql.Connection con = null; Class.forName("org.hsqldb.jdbcDriver"); con = DriverManager.getConnection("jdbc:hsqldb:hsql://localhost/", "SA", ""); Statement st=(Statement) con.createStatement(); ResultSet rs=((java.sql.Statement) st).executeQuery("select username,password from lgfrm"); String user=rs.getString(1); String pass=rs.getString(2); if(username.equals(user) &amp;&amp; password.equals(pass)) { Window.alert("success"); } } catch (Exception ae) {} return "success"; } } </code></pre> <p>------------------THE EXCEPTION LIST WHILE I'M TRYING TO VALIDATE A USER</p> <blockquote> <p>15:22:54.583 [ERROR] [helloworld] Uncaught exception escaped com.google.gwt.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:129) at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129) at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116) at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177) at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351) </p> </blockquote> <p>And many more like these.</p>
 

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