Why am I getting Class NotFound Exception using Tomcat in my webapp?

Question

I am using Gson Library 2.8.0 to convert JSON strings into Java Hashmap, Maven as a build system, Tomcat to run my code as webapp. IDE: IntelliJ Idea

The issue is whenever I run my code, execution stop and throws Class NotFound Exception.

Details as follows:

Tomcat Localhost logs ==>

java.lang.ClassNotFoundException: com.google.gson.Gson at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1309) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1137) at Test.doGet(Test.java:13) at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.base/java.lang.Thread.run(Thread.java:844)

Code ==>

import com.google.gson.Gson;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;

public class Test extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Gson gson=new Gson();
        String json = "{ \"color\" : \"Black\", \"type\" : \"BMW\" }";

    HashMap<String,Object> map=gson.fromJson(json, HashMap.class);
    System.out.println("This is the converted Gson result\n" +map);

    }
}

are you running on tomcat in intelliJ or are you deploying to tomcat manually? — Shiva
@secret super star Yes I am using tomcat in intelliJ. And what you mean by Gson is not available at runtime? Can You explain? — AKA
It means, while you run the application, the jvm is not able find the class Gson class in classpath and hence causing the issue. Try to clean the tomcat and run again. — Shiva

AKA AKA · Accepted Answer · 2018-11-20T14:18:47

0

votes

The issue is solved by putting Gson library files into the lib folder of Tomcat.

Why am I getting Class NotFound Exception using Tomcat in my webapp?

1 Answers