title: IllegalStateException when click on button in android hello world program
body: <p>I'm new to android and I'm trying to implement MyFirstApp given on android google developers site, So app contains one textbox and button, if you enter any text in textfield and click on button it displays same content on screen, but having problem when i clicked on send button.
      Please guide me how to solve this problem. </p>
  
  <p>Following exceptions:</p>
  
  <pre><code>&lt;p&gt;03-15 18:00:03.430: E/AndroidRuntime(592): FATAL EXCEPTION: main&lt;/p&gt;
  &lt;p&gt;03-15 18:00:03.430: E/AndroidRuntime(592): java.lang.IllegalStateException:Could not find a method MainActivity.sendMessage(View) in the activity class com.example.myfirstapp.DisplayMessageActivity for onClick handler on view class android.widget.Button&lt;/p&gt;
  &lt;p&gt;03-15 18:00:03.430: E/AndroidRuntime(592):   at android.view.View$1.onClick(View.java:3031)&lt;/p&gt;
  &lt;p&gt;03-15 18:00:03.430: E/AndroidRuntime(592):   at android.view.View.performClick(View.java:3511)&lt;/p&gt;
  </code></pre>
  
  <p>Here are two activities:<br>
   1.DisplayMessageActivity 
   this is activity mentioned in android manifest file . 
   This implement layout part</p>
  
  <pre><code>       public class DisplayMessageActivity extends Activity {
  
          @Override
           protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
  
  
  
          // Get the message from the intent
          Intent intent = getIntent();
          String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
  
          // Create the text view
          TextView textView = new TextView(this);
          textView.setTextSize(40);
          textView.setText(message);
  
          // Set the text view as the activity layout
          setContentView(textView);
  
          setContentView(R.layout.activity_display_message_1);
  
      }
         }
  </code></pre>
  
  <p>2.MainActivity<br>
  this is activity implement sendmessage function that is called when users clicked on    button . </p>
  
  <pre><code>      public class MainActivity extends Activity {
  
      public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
  
      /** Called when the user clicks the Send button */
      public void sendMessage(View view) {
          // Do something in response to button
          Intent intent = new Intent(this, DisplayMessageActivity.class);
          EditText editText = (EditText) findViewById(R.id.edit_message);
          String message = editText.getText().toString();
          intent.putExtra(EXTRA_MESSAGE, message);
          startActivity(intent);
      }
  
  
  }
  </code></pre>
  
  <p>Android Manifest xml file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.myfirstapp"
      android:versionCode="1"
      android:versionName="1.0" &gt;
  
      &lt;uses-sdk android:minSdkVersion="8" android:targetSdkVersion="11" /&gt;
  
      &lt;application
          android:allowBackup="true"
          android:icon="@drawable/ic_launcher"
          android:label="@string/app_name"
          android:theme="@style/AppTheme" &gt;
          &lt;activity
              android:name="DisplayMessageActivity"
              android:label="@string/title_activity_display_message"&gt;
             &lt;intent-filter &gt;
                  &lt;action android:name="android.intent.action.MAIN" /&gt;
                  &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;/intent-filter&gt; 
          &lt;/activity&gt;
      &lt;/application&gt;
  
  &lt;/manifest&gt;
  </code></pre>
  
  <p>And Layout xml file:</p>
  
  <pre><code> &lt;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" &gt;
  
      &lt;EditText android:id="@+id/edit_message"
          android:layout_weight="1"
          android:layout_width="0dp"
          android:layout_height="wrap_content"
          android:hint="@string/edit_message" /&gt;
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="@string/button_send" 
          android:onClick="sendMessage"/&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>