java - Read android assets files throw NullPointerException -

i working on android automation test, create test project in eclipse. (in automation, packed apk , deploy onto emulator) , in project, want read xml file in assets folder. put xml file "mytest.xml" directly in folder assets. , want load , parse. seems nullpointerexception. below code

1.the function defined in class osncommonlib.

public class osncommonlib extends activity {     public  string readtranslationfile(string filename,string transunitid)      {         if(doc == null)             {                 try                     {                     inputstream in = getassets().open(filename);                     documentbuilderfactory factory = documentbuilderfactory.newinstance();                      documentbuilder builder = factory.newdocumentbuilder();                      doc = builder.parse(in);                      }                      catch ( exception e )                     {                         system.out.println("mytest catch" + e.tostring() );                         e.printstacktrace();                     }                 }                   org.w3c.dom.element root = doc.getdocumentelement();                 nodelist nodes = root.getelementsbytagname( "trans-unit" );             .......                 }                 ....     }   

and function above called in java class

public class tc01_osndemo extends activityinstrumentationtestcase2 { osncommonlib ocl = new osncommonlib(); ... public void testsortbybutton(){      ....         string getstr = ocl.readtranslationfile("mytest","osn_menu_sortby");         assert.asserttrue(solo.searchtext(getstr));     ... } 

and in catch, java.lang.nullpointerexception. means can't load file? tried many times , still same errors.

can give suggestions issue?

besides: here full log

java.lang.nullpointerexception @ com.stg.osn.lib.osncommonlib.readtranslationfile(osncommonlib.java:107) --> **point org.w3c.dom.element root = doc.getdocumentelement();**  @ com.sgt.osn.junit.test.tc01_osndemo.testsortbybutton(tc01_osndemo.java:142) @ java.lang.reflect.method.invokenative(native method) @ android.test.instrumentationtestcase.runmethod(instrumentationtestcase.java:214) @ android.test.instrumentationtestcase.runtest(instrumentationtestcase.java:199) @ android.test.activityinstrumentationtestcase2.runtest(activityinstrumentationtestcase2.java:192) @ android.test.androidtestrunner.runtest(androidtestrunner.java:190) @ android.test.androidtestrunner.runtest(androidtestrunner.java:175) @ android.test.instrumentationtestrunner.onstart(instrumentationtestrunner.java:555) @ android.app.instrumentation$instrumentationthread.run(instrumentation.java:1661) 

at last, problem sovled. extend test case on instruments, should use below method call: inputstream in = getinstrumentation().getcontext().getassets().open("mytest.xml"); useful link http://developer.android.com/reference/android/test/instrumentationtestcase.html http://www.mail-archive.com/android-developers@googlegroups.com/msg62671.html

thanks all!!!

you can try this..

public string readdatafromassets(string file) {     try {       inputstream = getassets().open(file);       bufferedreader reader = new bufferedreader(new inputstreamreader(is));       stringbuilder builder = new stringbuilder();        string line = null;       try {         while ((line = reader.readline()) != null) {           builder.append(line);           // builder.append("\n"); // append new line         }       } catch (ioexception e) {          e.printstacktrace();       } {         try {           is.close();         } catch (ioexception e) {           e.printstacktrace();         }       }        return builder.tostring();            } catch (ioexception e) {        e.printstacktrace();     }     return null;   }