title: Can't resolve symbol 'SecondActivity' Validates resource references inside Android XML files
body: <p>I'm new to Android Application development. I just added another activity tag in my AndroidManifest.xml file but its gives me the following message : Can't resolve symbol 'SecondActivity' Validates resource references inside Android XML files.</p>
  
  <p>I want to know why is this message getting displayed? </p>
  
  <p>Here is my 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.aupadhyay.myfirstapp"&gt;
  
      &lt;application
          android:allowBackup="true"
          android:icon="@mipmap/amiticon"
          android:label="@string/app_name"
          android:supportsRtl="true"
          android:theme="@style/AppTheme"&gt;
  
          &lt;activity android:name=".MainActivity"&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=".SecondActivity"&gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="anything" /&gt;
                  &lt;category android:name="android.intent.category.DEFAULT" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt;
  
      &lt;/application&gt;
  
  &lt;/manifest&gt;
  </code></pre>
  
  <p>And this is my SecondActivity.java file :</p>
  
  <pre><code>import android.support.v7.app.AppCompatActivity;
  
  
  public class SecondActivity extends AppCompatActivity {
  
  }
  </code></pre>
  
  <p>Picture : 
  <a href="https://i.stack.imgur.com/KF4Sm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KF4Sm.png" alt="enter image description here"></a></p>