javadictionary

Is there an error with my code to put data in map?

I can't see the error of my code, I hope you can find it!

Language: Java IDE: Eclipse

I've created an object. This object contains this data:

public class ObjectTypeBean {
   private  Map<String, String> connectedOperators = new HashMap<String, String>();

   public Map<String, String> getConnectedOperators() {
       return connectedOperators;
   }

   public void setConnectedOperators(String operatorId, String label) {
       this.connectedOperators.put(operatorId, label);
    }
}

Then I've created a list of this object-class

List<ObjectTypeBean> name= new ArrayList<ObjectTypeBean>();

And I'm trying to add new Data to the map. I'm trying it like this:

for(ObjectTypeBean n:name){
   n.setConnectedOperators("one", "two");
}

But as soon as I tun this I get a 

java.lang.UnsupportedOperationException
at java.base/java.util.AbstractMap.put(AbstractMap.java:209)
    at ObjectTypeBean.setConnectedOperators(ObjectTypeBean.java:356)
    at MyServlet.doPost(MyServlet.java:372)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    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:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at CharsetFilter.doFilter(CharsetFilter.java:31)
    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:200)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:836)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1839)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Thread.java:834).
Solution

  • The problem was that I'm using a builder in my ObjectTypeBean-Object. The builder creates an Collections.emptyMap() so that the map can be empty.

    I've removed the connectedOperators-Map from the builder and there is no error anymore.