classNotFoundException GWTBridge

Question

im working on a gwt webapp

and while working on it im getting this exception while trying to get a XML file from a URL in a remove servlete.

i dont know much about the underworkings of gwt, maybe someone can help me out

this is the code to get the data from the url

public static String readURL(String path) throws IOException{
    String data = "";

    URL url = new URL(path);
    URLConnection conn = url.openConnection();
    BufferedReader br = new BufferedReader(new InputStreamReader(
            conn.getInputStream()));

    String line;

    while ((line = br.readLine()) != null) {
        data += line;
    }
    br.close();

    System.out.println(data.length());

    return data;
}

and this is the error im getting

        SEVERE: javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
    com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract void com.cpsc310.sc2.client.RouteService.storeParsedData()' threw an unexpected exception: java.lang.NoClassDefFoundError: com/google/gwt/core/client/GWTBridge
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:389)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:579)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:61)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:409)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: java.lang.NoClassDefFoundError: com/google/gwt/core/client/GWTBridge
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:169)
    at com.google.appengine.tools.development.agent.runtime.RuntimeHelper.checkRestricted(RuntimeHelper.java:70)
    at com.google.appengine.tools.development.agent.runtime.Runtime.checkRestricted(Runtime.java:64)
    at com.google.gwt.xml.client.impl.XMLParserImpl.<clinit>(XMLParserImpl.java:29)
    at com.google.gwt.xml.client.XMLParser.<clinit>(XMLParser.java:28)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:169)
    at com.google.appengine.tools.development.agent.runtime.RuntimeHelper.checkRestricted(RuntimeHelper.java:70)
    at com.google.appengine.tools.development.agent.runtime.Runtime.checkRestricted(Runtime.java:64)
    at com.cpsc310.sc2.server.parser.BikeRouteParser.parseRoutesbyDOM(BikeRouteParser.java:39)
    at com.cpsc310.sc2.server.RouteServiceImpl.storeParsedData(RouteServiceImpl.java:93)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:115)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:561)
    ... 38 more
Caused by: java.lang.ClassNotFoundException: com.google.gwt.core.client.GWTBridge
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:213)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

Is your code running on the server side or the client side? – SteveP Mar 16 '13 at 09:17 — SteveP, Mar 16 '13 at 09:17
that code that i pasted should be called on the server side – Pita Mar 17 '13 at 19:29 — Pita, Mar 17 '13 at 19:29

score 2 · Answer 1 · answered Mar 16 '13 at 09:49

2

As a general rule, you cannot use a class that's in a client package outside of a GWT client context (i.e. server-side)
(this is a rule we're trying to apply globally across gwt-user.jar, there are a few exceptions but they're mostly implementation details)

If you want to parse XML on your server, use javax.xml, not com.google.gwt.xml.client.

answered Mar 16 '13 at 09:49

Thomas Broyer

64,353
7
91
164

I thought the way to do it is to set up a service, and then the interface of the service will be in client, while the implementation is in server. at least thats how they did it in the tutorials – Pita Mar 17 '13 at 04:32
An interface is different, it doesn't contain _code_. BTW, many people now put their RPC interfaces in a `shared` package. – Thomas Broyer Mar 17 '13 at 22:53
I found that I can instantiate a GWT class inside a method of a shared entity, but cannot place it as a member of the class. As long as you call it from the client side it works fine. – slugmandrew Oct 28 '13 at 16:39
It'll actually depend on the JVM you use. OpenJDK and Sun/Oracle JVMs work, but I've heard others will fail early (trying to resolve native deps at class load time, rather than method call time) – Thomas Broyer Oct 28 '13 at 17:50

score 0 · Answer 2 · answered Apr 22 '15 at 07:43

Add the below in your project (make sure the package is right):

package com.google.gwt.core.client;
import com.google.gwt.core.shared.*;
/**
* Date: 1/17/13
* Time: 12:37 PM
* This class is used for fixing class not found com.google.gwt.core.client.GWTBridge;
*
* This is only needed for GXT 2 to work. Once we remove GXT2, this can be removed also.
*/
public abstract class GWTBridge extends com.google.gwt.core.shared.GWTBridge {
}

Original: http://alexluca.com/2013/01/17/gwt-25-and-extgwt-224-classnotfoundexception-comgooglegwtcoreclientgwtbridge/

classNotFoundException GWTBridge

2 Answers2

Linked