Archive for the ‘java’ Category.

« Previous Entries

Opening a URL connection in your mobile phone

June 15, 2010, 9:35 AM

Streams can be opened in several ways

1. HTTP communication:

Connection hc = Connector.open("http://www.wirelessdevnet.com");

2. Stream-based Socket communication:

Connection sc = Connector.open("socket://localhost:9000");

3. Datagram-based socket communication:

Connection dc = Connector.open("datagram://:9000");

4. Serial port communication:

Connection cc = Connector.open("comm:0;baudrate=9000");

5. File I/O

Connection fc = Connector.open("file://foo.dat");

I have used the HTTP communication.

HttpConnection c = (HttpConnection) Connector.open(url.getString());
this.responseCode = c.getResponseCode();
c.close();

While running, I got a warning in the log says…

Warning: To avoid potential deadlock, operations that may block, such as networking,
should be performed in a different thread than the commandAction() handler.

In addition, the phone emulator is not responding for the alert :( 

mobiletest Midlet Suite wants to connect to http:///...... using airtime. This may result in charges.
Is it OK to use airtime?

No response for this alert when I press yes or no several times!

http://forums.sun.com/thread.jspa?threadID=5339547

We need to write the HTTP connection in a separate thread, so that the main thread wont get blocked with it.

———
Ref. http://www.wirelessdevnet.com/channels/java/features/j2me_http.phtml

Tags: ,
Category: J2ME  |  Comments Off

Expression eKey is undefined on line 71, column 63 in template/simple/fielderror.ftl

May 12, 2010, 3:40 PM

This is one nasty exception occured due to carelessness.  I have added one field error in my action.

super.addFieldError("userName", "User name is null");

Instead of the field name “userName”, I have given the variable itself :) 

super.addFieldError(userName, "User name is null");

Replacing this removed this error.

10:40:24,859        ERROR runtime:96 -
Expression eKey is undefined on line 71, column 63 in template/simple/fielderror.ftl.
The problematic instruction:
----------
==> assignment: eValue=fieldErrors[eKey] [on line 71, column 33 in template/simple/fielderror.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression eKey is undefined on line 71, column 63 in template/simple/fielderror.ftl.
 at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:124)
 at freemarker.core.DynamicKeyName._getAsTemplateModel(DynamicKeyName.java:85)
 at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
 at freemarker.core.Assignment.accept(Assignment.java:90)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
 at freemarker.core.Environment.visit(Environment.java:415)
 at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.IfBlock.accept(IfBlock.java:82)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.Environment.process(Environment.java:188)
 at freemarker.template.Template.process(Template.java:237)
 at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:182)
 at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:559)
 at org.apache.struts2.components.UIBean.end(UIBean.java:513)
 at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
 at org.apache.jsp.index_jsp._jspx_meth_s_005ffielderror_005f0(index_jsp.java:193)
 at org.apache.jsp.index_jsp._jspx_meth_s_005fform_005f0(index_jsp.java:132)
 at org.apache.jsp.index_jsp._jspService(index_jsp.java:78)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
 at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
 at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
 at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
 at org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:154)
 at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
 at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:361)
 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:265)
 at com.eginnovations.common.interceptor.AuthorizationInterceptor.intercept(AuthorizationInterceptor.java:42)
 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
 at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
 at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:468)
 at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
 at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:76)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
 at java.lang.Thread.run(Unknown Source)
May 12, 2010 10:40:24 AM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
Expression eKey is undefined on line 71, column 63 in template/simple/fielderror.ftl.
The problematic instruction:
----------
==> assignment: eValue=fieldErrors[eKey] [on line 71, column 33 in template/simple/fielderror.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression eKey is undefined on line 71, column 63 in template/simple/fielderror.ftl.
 at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:124)
 at freemarker.core.DynamicKeyName._getAsTemplateModel(DynamicKeyName.java:85)
 at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
 at freemarker.core.Assignment.accept(Assignment.java:90)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
 at freemarker.core.Environment.visit(Environment.java:415)
 at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.IfBlock.accept(IfBlock.java:82)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.MixedContent.accept(MixedContent.java:92)
 at freemarker.core.Environment.visit(Environment.java:208)
 at freemarker.core.Environment.process(Environment.java:188)
 at freemarker.template.Template.process(Template.java:237)
 at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:182)
 at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:559)
 at org.apache.struts2.components.UIBean.end(UIBean.java:513)
 at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
 at org.apache.jsp.index_jsp._jspx_meth_s_005ffielderror_005f0(index_jsp.java:193)
 at org.apache.jsp.index_jsp._jspx_meth_s_005fform_005f0(index_jsp.java:132)
 at org.apache.jsp.index_jsp._jspService(index_jsp.java:78)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
 at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
 at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
 at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
 at org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:154)
 at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
 at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:361)
 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:265)
 at com.eginnovations.common.interceptor.AuthorizationInterceptor.intercept(AuthorizationInterceptor.java:42)
 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
 at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
 at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:468)
 at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
 at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:76)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
 at java.lang.Thread.run(Unknown Source)
Tags:
Category: Errors, struts  |  Comments Off

exec – IllegalThreadStateException: process has not exited

April 29, 2010, 11:43 PM

This is one nasty exception I experienced today.

I execute one .executable file from java. Reading the inputstream and the error stream with two different threads (why). I wait till ‘join’ing the thread then I took the process exit value.

processLogThread.join();
errorLogThread.join();
 try {
 logger.info("Thread status:"+processLogThread.isAlive()+" "+errorLogThread.isAlive());
 logger.info("Process exit value:"+p.exitValue());
 } catch (Exception e) {
 logger.error("Error while reading process exit value", e);
 }

Unfortunately, it threw the following exception. The streams are closed. Threads are dead. But it says process has not exited. aaw!!

18:19:39,802         INFO Utilities:432 - Thread status:false false
18:19:39,805        ERROR Utilities:435 - Error while reading process exit value
java.lang.IllegalThreadStateException: process has not exited
 at java.lang.ProcessImpl.exitValue(Native Method)
 at com.eginnovations.license.util.Utilities.genLicense5(Utilities.java:433)
Tags: ,
Category: Errors, java  |  Comments Off

JVM Monitoring

April 29, 2010, 5:23 PM

http://blogs.sun.com/alanb/entry/heap_dumps_are_back_with

Will write in detail soon!

Category: java  |  Comments Off

Clojure’s Approach to Polymorphism: Method Dispatch

April 27, 2010, 8:16 PM

I came across the following article on Clojure’s Approach to Polymorphism: Method Dispatch. Still I couldn’t understand how it is more advantageous against single dispatch in terms of complexity, resource consumption!!!

http://www.developer.com/lang/other/article.php/10942_3878656_1/Clojures-Approach-to-Polymorphism-Method-Dispatch.htm

Still I feel adding more rules will consume similar man hours! any comments?

Clojure’s Approach to Polymorphism: Method Dispatch

Tags: , ,
Category: java  |  Comments Off
« Previous Entries