java - NullPointerException causing app to instantly crash -

my apologies bad question title.

my problem app keeps instantly crashing once action performed. when read error, i'm seeing nullpointerexception reason crashing.

the error states takes place in main.java @ line 48. here full main.java:

 package com.fuzzyapplications.tutorial.youtube.app;   import android.content.intent;  import android.support.v7.app.actionbaractivity;  import android.os.bundle;  import android.view.menu;  import android.view.menuitem;  import android.view.view;  import android.widget.edittext;  public class main extends actionbaractivity {  public static final string extra_message = "com.fuzzyapplications.practice.app.message";   @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);  }   @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); }  public void sendmessage(view view){     intent intent = new intent(this, displaymessageactivity.class);      edittext edittext = (edittext) findviewbyid(r.string.edit_message);      string message = edittext.gettext().tostring();      intent.putextra(extra_message, message);      startactivity(intent);    } 

}

also, here activity should activated (once button pushed

package com.fuzzyapplications.tutorial.youtube.app;    import android.content.intent;   import android.support.v7.app.actionbaractivity;   import android.os.bundle;   import android.view.menu;   import android.view.menuitem;   import android.widget.textview;    public class displaymessageactivity extends actionbaractivity {  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      intent intent = getintent();     string message = intent.getstringextra(main.extra_message);     textview textview = new textview(this);     textview.settextsize(40);     textview.settext(message);     setcontentview(textview); }   @override public boolean oncreateoptionsmenu(menu menu) {      // inflate menu; adds items action bar if present.     getmenuinflater().inflate(r.menu.display_message, 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); }   } 

hope enough information you! new android i'm not sure how information should given problem, if don't have enough information please let me know! again.

edit: logcat info , layout info added!

logcat:

   fatal exception: main     java.lang.illegalstateexception: not execute method of activity             @ android.view.view$1.onclick(view.java:3802)             @ android.view.view.performclick(view.java:4437)             @ android.view.view$performclick.run(view.java:18365)             @ android.os.handler.handlecallback(handler.java:725)             @ android.os.handler.dispatchmessage(handler.java:92)             @ android.os.looper.loop(looper.java:137)             @ android.app.activitythread.main(activitythread.java:5285)             @ java.lang.reflect.method.invokenative(native method)             @ java.lang.reflect.method.invoke(method.java:511)             @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1102)             @ com.android.internal.os.zygoteinit.main(zygoteinit.java:869)             @ dalvik.system.nativestart.main(native method)      caused by: java.lang.reflect.invocationtargetexception             @ java.lang.reflect.method.invokenative(native method)             @ java.lang.reflect.method.invoke(method.java:511)             @ android.view.view$1.onclick(view.java:3797)             at android.view.view.performclick(view.java:4437)             at android.view.view$performclick.run(view.java:18365)             at android.os.handler.handlecallback(handler.java:725)             at android.os.handler.dispatchmessage(handler.java:92)             at android.os.looper.loop(looper.java:137)             at android.app.activitythread.main(activitythread.java:5285)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:511)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1102)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:869)             at dalvik.system.nativestart.main(native method)      caused by: java.lang.nullpointerexception             @ com.fuzzyapplications.tutorial.youtube.app.main.sendmessage(main.java:49)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:511)             at android.view.view$1.onclick(view.java:3797)             at android.view.view.performclick(view.java:4437)             at android.view.view$performclick.run(view.java:18365)             at android.os.handler.handlecallback(handler.java:725)             at android.os.handler.dispatchmessage(handler.java:92)             at android.os.looper.loop(looper.java:137)             at android.app.activitythread.main(activitythread.java:5285)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:511)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1102)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:869)             at dalvik.system.nativestart.main(native method) 

layout files:

main:

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal" >  <edittext     android:id="@+id/edit_message"     android:layout_weight="1"     android:layout_width="0dp"     android:layout_height="wrap_content"     android:hint="@string/edit_message"/>  <button     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="@string/button_send"     android:onclick="sendmessage"     />     </linearlayout> 

messagesendactivity layout:

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:paddingleft="@dimen/activity_horizontal_margin"     android:paddingright="@dimen/activity_horizontal_margin"     android:paddingtop="@dimen/activity_vertical_margin"     android:paddingbottom="@dimen/activity_vertical_margin"     tools:context="com.fuzzyapplications.practice.app.displaymessageactivity">  <textview     android:text="@string/hello_world"     android:layout_width="wrap_content"     android:layout_height="wrap_content" />   </relativelayout> 

you're trying refer reference string, doesn't exist in r.java, instead of reference id, declared in xml layout android:id="@+id/edit_message". causes nullpointerexception. use:

edittext edittext = (edittext) findviewbyid(r.id.edit_message); 

instead of:

edittext edittext = (edittext) findviewbyid(r.string.edit_message);