java - App cannot pass values between activities -

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i working on app in user inputs number 1 activity, , number shows on next activity. have far.

first activity: entertext.java

public class entertext extends activity {      //this string passed next activity     public static string mynumber = "com.example.listviewexplorer.message";      @override     protected void oncreate(bundle savedinstancestate) {             super.oncreate(savedinstancestate);             setcontentview(r.layout.activity_enter_text);     }      @override     public boolean oncreateoptionsmenu(menu menu) {         // inflate menu; adds items action bar if present.         getmenuinflater().inflate(r.menu.enter_text, menu);         return true;     }      //this onclick, button invoke sendmessage     //sendmessage supposed start next activity     public void sendmessage(view view){         intent intent = new intent (this, displaytext.class);         edittext edittext = (edittext) findviewbyid(r.id.edittext1);         mynumber = edittext.gettext().tostring();         intent.putextra("mynumber",mynumber);         startactivity(intent);     }  }

second activity: displaytext.java

public class displaytext extends activity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);          bundle extras=getintent().getextras();         string mynumber = extras.getstring("mynumber");         textview textview = (textview)findviewbyid(r.id.textview1);             textview.settext(entertext.mynumber);          setcontentview(r.layout.activity_display_text);         // show button in action bar.         setupactionbar();     } }

the problem app crashes when press button on first activity , calls sendmessage; second activity isn't displayed.

does know why occurring?

logcat posted below.

get it!

05-29 11:57:59.385: w/dalvikvm(3046): threadid=1: thread exiting uncaught exception (group=0x42d5d140) 05-29 11:57:59.425: e/androidruntime(3046): fatal exception: main 05-29 11:57:59.425: e/androidruntime(3046): process: com.example.listviewexplorer, pid: 3046 05-29 11:57:59.425: e/androidruntime(3046): java.lang.runtimeexception: unable start activity componentinfo{com.example.listviewexplorer/com.example.listviewexplorer.displaytext}: java.lang.nullpointerexception 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activitythread.performlaunchactivity(activitythread.java:2195) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activitythread.handlelaunchactivity(activitythread.java:2245) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activitythread.access$800(activitythread.java:135) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activitythread$h.handlemessage(activitythread.java:1196) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.os.handler.dispatchmessage(handler.java:102) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.os.looper.loop(looper.java:136) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activitythread.main(activitythread.java:5017) 05-29 11:57:59.425: e/androidruntime(3046):     @ java.lang.reflect.method.invokenative(native method) 05-29 11:57:59.425: e/androidruntime(3046):     @ java.lang.reflect.method.invoke(method.java:515) 05-29 11:57:59.425: e/androidruntime(3046):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:779) 05-29 11:57:59.425: e/androidruntime(3046):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:595) 05-29 11:57:59.425: e/androidruntime(3046):     @ dalvik.system.nativestart.main(native method) 05-29 11:57:59.425: e/androidruntime(3046): caused by: java.lang.nullpointerexception 05-29 11:57:59.425: e/androidruntime(3046):     @ com.example.listviewexplorer.displaytext.oncreate(displaytext.java:21) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activity.performcreate(activity.java:5231) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1087) 05-29 11:57:59.425: e/androidruntime(3046):     @ android.app.activitythread.performlaunchactivity(activitythread.java:2159) 05-29 11:57:59.425: e/androidruntime(3046):     ... 11 more

you need assign layout before using it.

@override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     // assign layout     setcontentview(r.layout.activity_display_text);     // can use     textview textview = (textview)findviewbyid(r.id.textview1);     textview.settext(entertext.mynumber);     ... }

since layout has not been defined @ stage null , when try access views inside nullpointerexception thrown.


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