sqlite - Android huge JSONObject toString goes OutOfMemoryError -

i need read lot of data sqlite database , create formatted json.

i'm achieving having object called requestpayload which contains arraylists in put data read sqlite.

the requestpayload class has parsejson() method returns jsonobject on call tostring() method obtain json string got written on file.

now, when i've got "small" quantities of data in sqlite goes fine. when i've got lot of data happens:

06-28 09:55:34.121 10857-6799/it.example.sampler e/androidruntime: fatal exception: thread-195240     process: it.example.sampler, pid: 10857     theme: themes:{com.cyanogenmod.trebuchet=overlay:system, com.android.settings=overlay:system, default=overlay:system, iconpack:system, fontpkg:system, com.android.systemui=overlay:system, com.android.systemui.navbar=overlay:system}     java.lang.outofmemoryerror: failed allocate 52962812 byte allocation 16764752 free bytes , 41mb until oom       @ java.lang.stringfactory.newstringfromchars(native method)       @ java.lang.abstractstringbuilder.tostring(abstractstringbuilder.java:629)       @ java.lang.stringbuilder.tostring(stringbuilder.java:663)       @ org.json.jsonstringer.tostring(jsonstringer.java:430)       @ org.json.jsonobject.tostring(jsonobject.java:690)       @ it.example.sampler.controllers.network.requestbodyencoder.serialise(requestbodyencoder.java:69)       @ it.example.sampler.controllers.network.requestbodyencoder.createpacket(requestbodyencoder.java:50)       @ it.example.sampler.services.filestorerunnable.run(filestorerunnable.java:57)       @ java.lang.thread.run(thread.java:818)  06-28 09:55:34.509 10857-10857/it.example.sampler e/windowmanager: android.view.windowleaked: activity it.example.sampler.ui.startsamplingactivity has leaked window com.android.internal.policy.phonewindow$decorview{74710d v.e...... r......d 0,0-1026,494} added here     @ android.view.viewrootimpl.<init>(viewrootimpl.java:372)     @ android.view.windowmanagerglobal.addview(windowmanagerglobal.java:299)     @ android.view.windowmanagerimpl.addview(windowmanagerimpl.java:86)     @ android.app.dialog.show(dialog.java:319)     @ it.example.sampler.ui.startsamplingactivity.executestop(startsamplingactivity.java:305)     @ it.example.sampler.ui.startsamplingactivity.onclickedbutton(startsamplingactivity.java:256)     @ it.example.sampler.ui.startsamplingactivity$3.onclick(startsamplingactivity.java:190)     @ android.view.view.performclick(view.java:5204)     @ android.view.view$performclick.run(view.java:21158)     @ android.os.handler.handlecallback(handler.java:739)     @ android.os.handler.dispatchmessage(handler.java:95)     @ android.os.looper.loop(looper.java:148)     @ android.app.activitythread.main(activitythread.java:5461)     @ java.lang.reflect.method.invoke(native method)     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:726)     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:616) 

now code:

the error line method:

private string serialise() throws jsonexception {     // serialise     string samplestring = mpayload.parsejson().tostring(); // line      logger.get().d(log_tag, "serialised payload: -> " + samplestring);     return samplestring; } 

and if got logcat correctly error during execution of tostring() method , appears json object big.

how can handle situation?

update: answer @yashjain comment asking size of jsonobject.

after sampling sampling lasted 2 hours had json containing:

• 12 jsonarray containing 155.432 floats
• 2 jsonarray containing 8.393 floats
• 1 jsonarray containing 8.393 custom object containing 5 floats each (and string)
• 1 2d array containing 155.432 ints

in terms of bytes since float made 4 bytes (i hope i've done calculus correctly) i've got circa:

(12 * 155432 * 4) + (2 * 8393 * 4) + (1 * 8393 * 5) + (1 * 155432 * 4) ~= 8.191.573 bytes 

update: i've been asked used compression algorithm. use zlib via deflater , deflateroutputstream java classes.

thus flow is:

• sample data -> store them in sqlite
• read sqlite -> build requestpayload object in memory
• convert requestpayload object jsonobject (with custom custom parser).
• convert jsonobject string (using jsonobject tostring() method)
• compress string bytes (using getbytes()) -> encode in base64
• send final base64 string server

edit: respond "possibile duplicate flag" haven't seen question during researches way didn't me since makes use of largeheap directive (which don't use). there's no accepted answer , answer doesn't provide practical solution.

sorry not giving more feedbacks i've been busy other works , got last in priority queue.

anyhow worked me using google gson library.

my serialisation method has become simply:

private string serialise() {     // serialise     return mpayload.tostringfromgson(); } 

and method tostringfromgson() in class payload is:

public string tostringfromgson() {     gsonbuilder gsonbuilder = new gsonbuilder();     gson gson = gsonbuilder.create();      return gson.tojson(this); } 

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anyhow think can considered temporary patch. in fact noticed memory used application increases dramatically during phase hence think problem postponed , occur heavier loads..