java - Anything wrong with modify an object inside a loop? -

- 

public collection<queuemetrics> getallgatewayqueuemetricscurrent(string keywords) {     queuemetrics qminput = null;     queuemetrics qmimport = null ;     queuemetrics qmreport = null ;     arraylist<queuemetrics> metrics = new arraylist<queuemetrics>();      (string keyword : keywords.split(",")){         consoleservicembean console = getconsoleservice(keyword);         populatemessagecountstr(qminput, keyword, console, "input");         populatemessagecountstr(qmimport, keyword, console, "import");         populatemessagecountstr(qmreport, keyword, console, "report");     }     metrics.add(qminput);     metrics.add(qmimport);     metrics.add(qmreport);      return metrics; }  private void populatemessagecountstr(queuemetrics qmetrics, string keyword, consoleservicembean console, string type) {     queuemetrics tempmetric = console.getgatewayqueuemetricscurrent(type, keyword);             if( qmetrics == null ){              qmetrics = tempmetric ;     }else{         qmetrics.setpendingmessagecountstr( qmetrics.getpendingmessagecountstr() + ", " + tempmetric.getpendingmessagecount());          }  }

i tried update qminput, qmimport , qmreport inside upper loop, calling populatemessagecountstr , passing in object updated. in next loop, same object updated 1 more time additional data. however, end result of program qminput, qmimport , qmreport null. knows why? provide more info, when change upper function little bit:

        qminput = populatemessagecountstr(qminput, keyword, console, "input");         qmimport = populatemessagecountstr(qmimport, keyword, console, "import");         qmreport = populatemessagecountstr(qmreport, keyword, console, "report");

and lower function returns updated queuemetrics instead of void. program works expcected. knows why original way didn't work? appreciate useful comments.

however, end result of program qminput, qmimport , qmreport null.

because, re-assigning passed queuemetrics reference in method new object if equal null, on first invocation. in case original reference still point null. , hence remain null on further invocation of method, condition qmetrics == null true.

since java passes reference value, re-assigning qmetrics different instance, change value of copy of reference passed. not modify reference value of original reference.

to solve issue, return modified reference method (change return type of populatemessagecounterstr() queuemetrics, , assign original reference on calling side.


Comments

Post a Comment

Popular posts from this blog

java - Run a .jar on Heroku -

-
i trying run .jar file on heroku, , can't find instructions anywhere on how this. have read wants me compile uploading heroku. possible, , if is, how this? if helps, trying run minecraft craftbukkit server, , don't have pom.xml file yet. you didn't provide details i'll try give , people reaches question way it. first of all, create heroku account , create heroku application (assumed have done that). second, need generate application jar , upload heroku. so, open terminal , install heroku cli (assuming unix terminal): $ sudo npm install -g heroku-cli you need have npm , nodejs installed, can check link: https://www.digitalocean.com/community/tutorials/how-to-install-node-js-on-ubuntu-16-04 once done that, can use npm update node version acceptable heroku-cli: $ sudo npm install -g n $ sudo n 7.10.0 and run: $ sudo npm install -g heroku-cli in order deploy jars, need install deploy plugin: $ sudo heroku plugins:install heroku-cli-deploy ...
Read more

java - Jtable duplicate Rows -

-
Image
when add new rows in jtable duplicate rows many times this method update jtable public final void tableaucomande(){ ((defaulttablemodel)tabcommande.getmodel()).getdatavector().clear(); session s=hibernateutil.getsessionfactory().opensession(); criteria cr1= s.createcriteria(commande.class); list <commande> lcs=cr1.list() ; criteria cr2= s.createcriteria(lignecommande.class); list <lignecommande> lck=cr2.list() ; if(lcs.size()!=0 && lck.size()!=0) { (commande lc:lcs) { for(lignecommande lig:lck){ ((defaulttablemodel)tabcommande.getmodel()).addrow(new object[]{ lc.getid_cmd(),lc.getnumcmd(),lc.getdate_cmd(),lc.getclient().getnomprenom(), lig.getproduit().getlib_prd(),lig.getquantite(),lig.getproduit().getid_prd() }); } } // tabcommande.setrowselectioninterval(tabcommande.getrowcount()-1,tabcommande.getrowcount()-1); } } this code add add data rows displaye...
Read more

validation - How to pass paramaters like unix into windows batch file -

-
i need pass various parameters .cmd file unix format file.cmd -configuration=value -source=value -flag but, try this: startlocal @echo off cls setlocal set cmdline=%* set configuration= set source= set badargs= set validation= goto main :splitargs echo splitargs(%*) if "%*" neq "" ( /f "tokens=1,2,* delims== " %%i in ("%*") call :assignkeyvalue %%i %%j & call :splitargs %%k ) goto :eof :assignkeyvalue echo assignkeyvalue(%1, %2) if /i %1==-configuration ( set configuration=%2 ) else if /i %1==-source ( set source=%2 ) else ( rem append unrecognised [key,value] badargs echo unknown key %1 set badargs=%badargs%[%1, %2] ) goto :eof :validate echo validating set validation=fail if defined configuration ( echo -configuration ok if defined source ( echo -source ok if not defined badargs ( set validation=success ) ) ) goto :eof :main cl...
Read more