title: Java Error "Unable to Find Symbol" with Android
body: <p>So I am attempting to make an Android App, but when I try to compile my project, I get the error:</p>
  
  <pre><code>DisplayMessageActivity.java :2 :Error - cannot find symbol
  "public class DisplayMessageActivity extends Activity {"
  
  symbol: class Activity
  </code></pre>
  
  <p>Here is my source code for DisplayMessageActivity.java(it's parent is MainActivity.java, which imports the android.app.Activity and android.os.Bundle packages):</p>
  
  <pre><code>public class DisplayMessageActivity extends Activity {
  @Override
  public 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);
  }
  }
  </code></pre>
  
  <p>Here is the AndroidManifest.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.HelloWorld"
    android:versionCode="1"
    android:versionName="1.0"&gt;
  &lt;application android:label="@string/app_name" android:icon="@drawable/ic_launcher" android:theme="@android:style/Theme.Holo"&gt;
      &lt;activity android:name="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=".DisplayMessageActivity"
          android:label="@string/title_activity_display_message"&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>Please help,</p>
  
  <p>Niro56</p>