Get IllegalArgumentException when trying to create a key for an object

Question

I am working on a Google App Engine and I am stuck at a certain point. I am trying to create a key for my object. Here is the code:

Element child = (Element) itr.next(); String name = ""; if(child.getQualifiedName().equals("name")){ name += child.getText(); } Key drugKey = KeyFactory.createKey("DrugTarget", name); 

I am 100% sure that child.getText () is not returning null. I already tested it. I have another piece of code that works great with Key. Both seem alike.

 String drug = req.getParameter("drugname"); Key drugKey = KeyFactory.createKey("DrugTarget", drug); 

I really did not understand why it gives an error. The first part of the code belongs to the Java class, and I call this class in the Java Servlet Class. The second is the Java Servlet class. But I think the problem is different. Could you help me? Thanks.

Edited Part:

 if(child.getQualifiedName().equals("name")){ if(child.getText() != null){ name = child.getText(); } else{ name = "asd"; } } 

I put this in my code, still getting a zero error. child.getText () does not return null, and the name is not equal to "asd".

Forgot to add an error message:

 Uncaught exception from servlet java.lang.IllegalArgumentException: name cannot be null or empty at com.google.appengine.api.datastore.KeyFactory.createKey(KeyFactory.java:73) at com.google.appengine.api.datastore.KeyFactory.createKey(KeyFactory.java:60) at guestbook.saxParser2.getDrug(saxParser2.java:42) at guestbook.SignGuestbookServlet.doPost(SignGuestbookServlet.java:77) 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$CachedChain.doFilter(ServletHandler.java:1166) at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:102) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35) 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 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.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:266) 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$RequestHandler.headerComplete(HttpConnection.java:923) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146) at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:447) at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454) at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461) at com.google.tracing.TraceContext.runInContext(TraceContext.java:703) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330) at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458) at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251) at java.lang.Thread.run(Thread.java:679) 

Answer 1

The error message states:

 Uncaught exception from servlet java.lang.IllegalArgumentException: name cannot be null or empty 

And your actual code:

 String name = ""; if(child.getQualifiedName().equals("name")){ name += child.getText(); } Key drugKey = KeyFactory.createKey("DrugTarget", name); 

So, in the if statement, the expression child.getQualifiedName().equals("name") is false, and the variable 'name' String is still an empty string ( String name = "" ). And this is what the error message was talking about: cannot be an empty string in Key Key drugKey = KeyFactory.createKey("DrugTarget", name); as a parameter.

EDIT: Try the following:

 Element child = (Element) itr.next(); String name = "defaultName"; if(child.getQualifiedName().equals("name")){ name = child.getText(); } Key drugKey = KeyFactory.createKey("DrugTarget", name); 

The problem is not that returning child.getText() with zero or not, the problem in the expression in your if statement will be false , so name += child.getText(); unavailable, and name is still an empty string.

 if(child.getQualifiedName().equals("name")){ name += child.getText(); } 

Answer 2

"cook" ready to eat.

 Element child = (Element) itr.next(); String name; if(child.getQualifiedName().equals("name")){ name = child.getText(); if(name!=null){ Key drugKey = KeyFactory.createKey("DrugTarget", name); } }