json - How to avoid unnecessary object creation in Java in a for loop -


i creating following json file using java

jsonobject json = new jsonobject(); jsonarray vertex = new jsonarray(); (int = 0; < num; i++) {     jsonobject usr1 = new jsonobject();     jsonobject usr2 = new jsonobject();      // string na="name"+i     usr1.put("type", "string");     usr1.put("value", "name" + i);     usr2.put("name", usr1);      usr2.put("_id", integer.tostring(i));     usr2.put("_type", "vertex");     // v2.put(usr2);     vertex.put(usr2);      // email     jsonobject usr3 = new jsonobject();     jsonobject usr4 = new jsonobject();     usr3.put("type", "string");     usr3.put("value", "email" + + "@gmail.com");     usr4.put("email", usr3);      usr4.put("_id", integer.tostring(i + num));     usr4.put("_type", "vertex");     vertex.put(usr4); } json.put("vertex", vertex);

the num can approx 60,000-200,000.

but on here creating java objects again , again, quite expensive. want object creation minimized don't want change code structure much. how can achieve without changing code structure much?

i'm using json* classes org.codehaus.jettison.json package.and have write file json object

for fast json generation without creating intermediate objects jsonwriter used:

stringwriter sw = new stringwriter(); jsonwriter writer = new jsonwriter(sw); writer.object().key("vertex").array(); (int = 0; < num; i++) {     writer         .object() // usr2             .key("name")                 .object() // usr1                     .key("type").value("string")                     .key("value").value("name"+i)                 .endobject()             .key("_id").value(integer.tostring(i))             .key("_type").value("vertex")         .endobject()         .object() // usr4             .key("email")                 .object() // usr3                     .key("type").value("string")                     .key("value").value("email"+i+"@gmail.com")                 .endobject()             .key("_id").value(integer.tostring(i+num))             .key("_type").value("vertex")         .endobject(); } writer.endarray().endobject(); string json = sw.tostring();

here stringwriter used store intermediate json text. alternatively may write directly file or network socket without keeping in memory @ all.


Comments

Post a Comment

Popular posts from this blog

html - Outlook 2010 Anchor (url/address/link) -

i'm trying link specific pdf page msoutlook'10 or msword'10, #page=... anchor particularly useful , works fine elsewhere. unfortunately when click [ctr-k] in outlook or winword, links re-formatted assuming unc path. pdf file located on shared drive. using "file:" prefix links open pdf in adobe reader (outside of browser), , "http:" open inside browser. issue seem need open in browser "file:" prefix in order anchor work. know anchors work inside browser. outlook uses windows/explorer default program (based on file extension) seems open in adobe reader neglecting anchor. is aware of solution, link specific page or bookmark of shared-pdf ms outlook and/or winword link? common references: mailermailer.com/...anchor-tags-html-emails campaignmonitor.com/...anchor-links-in-email-newsletters/ stackoverflow.com/...anchor-in-pdf-document
Read more

javascript - Why does running this loop 9 times take 100x longer than running it 8 times? -

consider code: test = function() { } t = new test(); (var = 0; < 8; i++) { result = t instanceof test; } if change number of iterations 8 9 , loop take 100 times longer complete in latest version of firefox (41.0.1). tested on 2 different pcs , magic limit 8. here jsperf test used: http://jsperf.com/instanceof-8-times-vs-9-times does have idea why might happen? seems specific instanceof . not happen if else object, example check property. note: filed bugzilla bug this. jan de mooij mozilla team has posted details in bugzilla thread . here's simplistic interpretation of highly technical answers: in i < 8 case, firefox smart enough hoist result = t instanceof test; statement out of loop (according tests, doesn't seem omit altogether). in i < 9 case, apparently doesn't optimization . why? reason not clear, related fact 9 iterations threshold above function considered "hot" enough run through jit compiler. i < 8 cas...
Read more

Getting gateway time-out Rails app with Nginx + Puma running on Digital Ocean -

following this guide setup app on digital ocean droplet, not working. site not loading , it's throwing: "gateway time-out". the puma server works, since ps aux | grep puma prints: root 15878 0.0 0.4 376832 2168 ? sl 12:50 0:00 puma 2.13.4 (unix:///var/www/myapp/shared/tmp/sockets/myapp-puma.sock) [20150930164940] root 15881 0.0 0.7 903676 3692 ? sl 12:50 0:06 puma: cluster worker 0: 15878 [20150930164940] root 24654 0.0 0.1 11748 916 pts/2 s+ 18:00 0:00 grep --color=auto puma my nginx config: user root; worker_processes 1; events { worker_connections 1024; } http { upstream puma { server unix:///var/www/myapp/shared/tmp/sockets/myapp-puma.sock; } server { listen 80; server_name myapp.com; root /var/www/myapp/current/public; access_log /var/www/myapp/current/log/access.log; error_log /...
Read more