title: Android startActivity exception
body: <p>I'm trying to start an activity from the <code>MainActivity</code> via the fab button. My code is below. The exception I get is:</p>
  
  <pre><code>ActivityNotFoundException: Unable to find explicit activity class //packagename; have you declared this activity in your AndroidManifest.xml?
  </code></pre>
  
  <p>Although the exception is pointing me to my android manifest, I did add the activity there, although perhaps not correctly. Here is my code:</p>
  
  <p>MainActivity.java</p>
  
  <pre><code>import android.content.Intent;
  import android.os.Bundle;
  import android.support.design.widget.FloatingActionButton;
  import android.support.design.widget.Snackbar;
  import android.support.v7.app.AppCompatActivity;
  import android.support.v7.widget.Toolbar;
  import android.view.View;
  import android.view.Menu;
  import android.view.MenuItem;
  
  public class MainActivity extends AppCompatActivity {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
      setSupportActionBar(toolbar);
  
      FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
  
      /*
      *  OnLongClick - start listening via Listen class
      * */
      fab.setOnLongClickListener(new View.OnLongClickListener() {
          @Override
          public boolean onLongClick(View view) {
  
              Intent intent = new Intent(getApplicationContext(), Listen.class);
  
              Snackbar.make(view, "Bluetooth authentication is on", Snackbar.LENGTH_LONG)
                      .setAction("Action", null).show();
              startActivity(intent);
              return true;
          }
      });
  
      fab.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
              Snackbar.make(view, "Bluetooth authentication turned off", Snackbar.LENGTH_LONG)
                      .setAction("Action", null).show();
          }
      });
  
  }
  </code></pre>
  
  <p>Listen.java</p>
  
  <pre><code>import android.app.Activity;
  import android.app.Notification;
  import android.app.NotificationManager;
  import android.app.PendingIntent;
  import android.content.Context;
  import android.content.Intent;
  import android.os.Bundle;
  
  import com.estimote.sdk.Beacon;
  import com.estimote.sdk.BeaconManager;
  import com.estimote.sdk.Region;
  import com.estimote.sdk.SystemRequirementsChecker;
  
  import java.util.List;
  import java.util.UUID;
  
  public class Listen extends Activity {
  
      private BeaconManager beaconManager;
      private Region region;
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          beaconManager = new BeaconManager(this);
  
          region = new Region("ranged region",
                  UUID.fromString("B9407F30-F5F8-466E-AFF9-25556B57FE6D"), null, null);
      }
  
  
      @Override
      protected void onResume() {
          super.onResume();
  
          SystemRequirementsChecker.checkWithDefaultDialogs(this);
  
          beaconManager.setMonitoringListener(new BeaconManager.MonitoringListener() {
              @Override
              public void onEnteredRegion(Region region, List&lt;Beacon&gt; list) {
                  showNotification(
                          "Welcome..",
                          "to the AccessLab!");
              }
              @Override
              public void onExitedRegion(Region region) {
                  showNotification(
                          "You've left the lab..",
                          "Goodbye!");
              }
          });
  
  
          beaconManager.connect(new BeaconManager.ServiceReadyCallback() {
              @Override
              public void onServiceReady() {
                  beaconManager.startMonitoring(region);
              }
          });
      }
  
  
  
      public void showNotification(String title, String message) {
          Intent notifyIntent = new Intent(this, MainActivity.class);
          notifyIntent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
          PendingIntent pendingIntent = PendingIntent.getActivities(this, 0,
                  new Intent[] { notifyIntent }, PendingIntent.FLAG_UPDATE_CURRENT);
          Notification notification = new Notification.Builder(this)
                  .setSmallIcon(android.R.drawable.ic_dialog_info)
                  .setContentTitle(title)
                  .setContentText(message)
                  .setAutoCancel(true)
                  .setContentIntent(pendingIntent)
                  .build();
          notification.defaults |= Notification.DEFAULT_SOUND;
          NotificationManager notificationManager =
                  (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
          notificationManager.notify(1, notification);
      }
  
  }
  </code></pre>
  
  <p>AndroidManifest.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="accesscontrol2016"&gt;
  
  &lt;application
  
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:supportsRtl="true"
      android:theme="@style/AppTheme"&gt;
      &lt;activity
          android:name=".MainActivity"
          android:label="@string/app_name"
          android:theme="@style/AppTheme.NoActionBar"&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=".Listen"
          android:label="@string/app_name"&gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.DEFAULT" /&gt;
              &lt;category android:name="accesscontrol2016.Listen" /&gt;
          &lt;/intent-filter&gt;
      &lt;/Activity&gt;
  &lt;/application&gt;
  </code></pre>
  
  <p></p>
  
  <p>As you can hopefully see I've added the <code>Listen</code> class to my activities in the Android Manifest. I'm not sure if I'm setting up my Intent properly, with <code>getApplicationContext()</code>. Any help much appreciated.</p>