java - Problems opening PDF from assets -

i have problem when trying open pdf (a.pdf) assets folder. thi java code:

package com.tischer.alessandro.ecocardiochecklist;   import android.content.context; import android.content.intent; import android.content.res.assetmanager; import android.net.uri; import android.os.bundle; import android.support.v7.app.appcompatactivity; import android.util.log; import java.io.file; import java.io.ioexception; import java.io.inputstream; import java.io.outputstream;  public class bibliografia extends appcompatactivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_bibliografia);         assetmanager assetmanager = getassets();          inputstream in = null;         outputstream out = null;         file file = new file(getfilesdir(), "a.pdf");         try         {             in = assetmanager.open("a.pdf");             out = openfileoutput(file.getname(), context.mode_world_readable);              copyfile(in, out);             in.close();             in = null;             out.flush();             out.close();             out = null;         } catch (exception e)         {             log.e("tag", e.getmessage());         }          intent intent = new intent(intent.action_view);         intent.setdataandtype(                 uri.parse("file://" + getfilesdir() + "/a.pdf"),                 "application/pdf");          startactivity(intent);     }      private void copyfile(inputstream in, outputstream out) throws ioexception     {         byte[] buffer = new byte[1024];         int read;         while ((read = in.read(buffer)) != -1)         {             out.write(buffer, 0, read);         }     }  } 

this logcat:

11/10 11:52:42: launching app cold swapped changes. $ adb shell start -n "com.tischer.alessandro.ecocardiochecklist/com.tischer.alessandro.ecocardiochecklist.splashscreen" -a android.intent.action.main -c android.intent.category.launcher client not ready yet..waiting process come online connected process 3259 on device nexus_5x_api_24 [emulator-5554] i/instantrun: instant run runtime started. android package com.tischer.alessandro.ecocardiochecklist, real application class null.                [ 11-10 10:52:44.162  1489: 1510 d/         ]               hostconnection::get() new host connection established 0x8d361440, tid 1510 w/art: before android 4.1, method android.graphics.porterduffcolorfilter android.support.graphics.drawable.vectordrawablecompat.updatetintfilter(android.graphics.porterduffcolorfilter, android.content.res.colorstatelist, android.graphics.porterduff$mode) have incorrectly overridden package-private method in android.graphics.drawable.drawable w/gralloc_ranchu: gralloc pipe failed                    [ 11-10 10:52:45.193  3259: 3259 d/         ]                   hostconnection::get() new host connection established 0x9d027140, tid 3259                     [ 11-10 10:52:45.239  3259: 3278 d/         ]                   hostconnection::get() new host connection established 0x9d0d6d40, tid 3278 i/openglrenderer: initialized egl, version 1.4 d/openglrenderer: swap behavior 1 d/openglrenderer: endallactiveanimators on 0x90937d80 (rippledrawable) handle 0x9d07eb80 e/tag: mode_world_readable no longer supported d/androidruntime: shutting down vm e/androidruntime: fatal exception: main                   process: com.tischer.alessandro.ecocardiochecklist, pid: 3259                   java.lang.runtimeexception: unable start activity componentinfo{com.tischer.alessandro.ecocardiochecklist/com.tischer.alessandro.ecocardiochecklist.bibliografia}: android.os.fileuriexposedexception: file:///data/user/0/com.tischer.alessandro.ecocardiochecklist/files/a.pdf exposed beyond app through intent.getdata()                       @ android.app.activitythread.performlaunchactivity(activitythread.java:2646)                       @ android.app.activitythread.handlelaunchactivity(activitythread.java:2707)                       @ android.app.activitythread.-wrap12(activitythread.java)                       @ android.app.activitythread$h.handlemessage(activitythread.java:1460)                       @ android.os.handler.dispatchmessage(handler.java:102)                       @ android.os.looper.loop(looper.java:154)                       @ android.app.activitythread.main(activitythread.java:6077)                       @ java.lang.reflect.method.invoke(native method)                       @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:865)                       @ com.android.internal.os.zygoteinit.main(zygoteinit.java:755)                    caused by: android.os.fileuriexposedexception: file:///data/user/0/com.tischer.alessandro.ecocardiochecklist/files/a.pdf exposed beyond app through intent.getdata()                       @ android.os.strictmode.onfileuriexposed(strictmode.java:1799)                       @ android.net.uri.checkfileuriexposed(uri.java:2346)                       @ android.content.intent.preparetoleaveprocess(intent.java:8933)                       @ android.content.intent.preparetoleaveprocess(intent.java:8894)                       @ android.app.instrumentation.execstartactivity(instrumentation.java:1517)                       @ android.app.activity.startactivityforresult(activity.java:4224)                       @ android.support.v4.app.basefragmentactivityjb.startactivityforresult(basefragmentactivityjb.java:48)                       @ android.support.v4.app.fragmentactivity.startactivityforresult(fragmentactivity.java:75)                       @ android.app.activity.startactivityforresult(activity.java:4183)                       @ android.support.v4.app.fragmentactivity.startactivityforresult(fragmentactivity.java:856)                       @ android.app.activity.startactivity(activity.java:4507)                       @ android.app.activity.startactivity(activity.java:4475)                       @ com.tischer.alessandro.ecocardiochecklist.bibliografia.oncreate(bibliografia.java:48)                       @ android.app.activity.performcreate(activity.java:6664)                       @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1118)                       @ android.app.activitythread.performlaunchactivity(activitythread.java:2599)                       @ android.app.activitythread.handlelaunchactivity(activitythread.java:2707)                        @ android.app.activitythread.-wrap12(activitythread.java)                        @ android.app.activitythread$h.handlemessage(activitythread.java:1460)                        @ android.os.handler.dispatchmessage(handler.java:102)                        @ android.os.looper.loop(looper.java:154)                        @ android.app.activitythread.main(activitythread.java:6077)                        @ java.lang.reflect.method.invoke(native method)                        @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:865)                        @ com.android.internal.os.zygoteinit.main(zygoteinit.java:755)  

i'm running android 7.0, app crashes older versions... where's problem?

you copy file application's private directory, no other apps can access. , try open file in app (it unable access file application's private directory).

to solve this, have few options:

1. copy file public directory, environment.getexternalstoragedirectory()
2. implement contentprovider in app

1st way easier, , go way if doing it.
2nd way more correct, overheat here me.