Android zxing throws NullPointerException -

i planing use zxing library provide qr code functionality in android app. able work, throws exception. using sample code provided library github link. can let me know causing exception?

links intentintegrator , intentresult classes.

sample code mainactiivity (used eclipse generate initial code):

package com.example.testapp;  import android.app.activity; import android.app.alertdialog; import android.os.bundle; import android.util.log; import android.view.menu; import android.view.menuitem; import android.view.view; import android.view.view.onclicklistener; import android.widget.button;  import com.google.zxing.integration.android.intentintegrator;  public class mainactivity extends activity {      private static final string tag = "mainactivity";      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          button b = (button) findviewbyid(r.id.button1);          b.setonclicklistener(new onclicklistener() {              @override             public void onclick(view v) {                 try {                     intentintegrator integrator = new intentintegrator(                             mainactivity.this);                     alertdialog d = integrator.sharetext("sample text here");                     d.show();                 } catch (exception e) {                     log.e(tag, log.getstacktracestring(e));                 }              }         });      }      @override     public boolean oncreateoptionsmenu(menu menu) {          // inflate menu; adds items action bar if present.         getmenuinflater().inflate(r.menu.main, menu);         return true;     }      @override     public boolean onoptionsitemselected(menuitem item) {         // handle action bar item clicks here. action bar         // automatically handle clicks on home/up button, long         // specify parent activity in androidmanifest.xml.         int id = item.getitemid();         if (id == r.id.action_settings) {             return true;         }         return super.onoptionsitemselected(item);     } } 

exception logcat:

04-09 13:08:13.923: e/mainactivity(27574): java.lang.nullpointerexception 04-09 13:08:13.923: e/mainactivity(27574):  @ com.example.testapp.mainactivity$1.onclick(mainactivity.java:38) 04-09 13:08:13.923: e/mainactivity(27574):  @ android.view.view.performclick(view.java:4633) 04-09 13:08:13.923: e/mainactivity(27574):  @ android.view.view$performclick.run(view.java:19330) 04-09 13:08:13.923: e/mainactivity(27574):  @ android.os.handler.handlecallback(handler.java:733) 04-09 13:08:13.923: e/mainactivity(27574):  @ android.os.handler.dispatchmessage(handler.java:95) 04-09 13:08:13.923: e/mainactivity(27574):  @ android.os.looper.loop(looper.java:157) 04-09 13:08:13.923: e/mainactivity(27574):  @ android.app.activitythread.main(activitythread.java:5356) 04-09 13:08:13.923: e/mainactivity(27574):  @ java.lang.reflect.method.invokenative(native method) 04-09 13:08:13.923: e/mainactivity(27574):  @ java.lang.reflect.method.invoke(method.java:515) 04-09 13:08:13.923: e/mainactivity(27574):  @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1265) 04-09 13:08:13.923: e/mainactivity(27574):  @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1081) 04-09 13:08:13.923: e/mainactivity(27574):  @ dalvik.system.nativestart.main(native method) 04-09 13:08:13.933: d/abslistview(27574): unregisterirlistener() called  04-09 13:08:14.518: d/abslistview(27574): onvisibilitychanged() called, visibility : 4 04-09 13:08:14.518: d/abslistview(27574): unregisterirlistener() called  

thanks in advance.

solution:

thank help.

as tanis.7x pointed out below, error line d.show().

i trying write root of issue understand it, correct me if wrong.

the method sharetext() returns dialogbox if , if cannot find package "com.google.zxing.client.android".

the dialog should used prompt user install application "barcode reader" playstore.

since had package (by including jar files in project), method returned null , made (stupid) error of calling method on that.

the sharetext() method not guaranteed return dialog.

as per documentation, sharetext() return:

the alertdialog shown user prompting them download app if prompt needed, or null otherwise

if user has app, there no need show dialog, , method return null.

also note dialog have been shown time method returns, not need show yourself. recommend looking through intentintegrator source more information.