title: Android first application String cannot be resolved or is not a field error
body: <p>I was going through this URL -<a href="http://developer.android.com/training/basics/firstapp/creating-project.html" rel="nofollow">http://developer.android.com/training/basics/firstapp/creating-project.html</a>
  and getting this error EXTRA_MESSAGE cannot be resolved or is not a field:</p>
  
  <p>Menifest</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="17" /&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="com.example.myfirstapp.MainActivity"
          android:label="@string/app_name" &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;activity
          android:name="com.example.myfirstapp.DisplayMessageActivity"
          android:label="@string/title_activity_display_message"
          android:parentActivityName="com.example.myfirstapp.MainActivity" &gt;
          &lt;meta-data
              android:name="android.support.PARENT_ACTIVITY"
              android:value="com.example.myfirstapp.MainActivity" /&gt;
      &lt;/activity&gt;
  &lt;/application&gt;
  
  &lt;/manifest&gt;
  </code></pre>
  
  <p>MainActivity.java</p>
  
  <pre><code>package com.example.myfirstapp;
  
  import android.os.Bundle;
  import android.view.View;
  import android.app.Activity;
  import android.view.Menu;
  import android.content.Intent;
  import android.widget.EditText;
  
  public class MainActivity extends Activity {
  public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
  
  
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  }
  
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.main, menu);
      return true;
  }
  
  
  public void sendMessage(View view) {
      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>}</p>
  
  <p>DisplayMessageActivity</p>
  
  <pre><code>package com.example.myfirstapp;
  
  import android.os.Bundle;
  import android.view.View;
  import android.app.Activity;
  import android.view.Menu;
  import android.content.Intent;
  import android.widget.EditText;
  import android.widget.TextView;
  
  import android.app.Activity;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.support.v4.app.NavUtils;
  import android.annotation.TargetApi;
  import android.os.Build;
  
  public class DisplayMessageActivity extends Activity {
  
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
  
      super.onCreate(savedInstanceState);
      Intent intent = getIntent();
      String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
      setContentView(R.layout.activity_display_message);
      // Create the text view
      TextView textView = new TextView(this);
      textView.setTextSize(40);
      textView.setText(message);
  
      // Show the Up button in the action bar.
      setupActionBar();
  
  }
  
  /**
   * Set up the {@link android.app.ActionBar}, if the API is available.
   */
  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
  private void setupActionBar() {
      if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.HONEYCOMB) {
          getActionBar().setDisplayHomeAsUpEnabled(true);
  }
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.display_message, menu);
  return true;
  }
  
  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
      switch (item.getItemId()) {
       case android.R.id.home:
          // This ID represents the Home or Up button. In the case of this
          // activity, the Up button is shown. Use NavUtils to allow users
          // to navigate up one level in the application structure. For
          // more details, see the Navigation pattern on Android Design:
          //
  
          //
          NavUtils.navigateUpFromSameTask(this);
          return true;
          }
          return super.onOptionsItemSelected(item);
      }
  
  }
  </code></pre>
  
  <p>Please guide.</p>