what is dollar sign do in the manifest.xml
<p><strong>Some explanations</strong> </p>

<p>I was looking for gaining administration permission from user in android and found <a href="https://developer.android.com/guide/topics/admin/device-admin.html" rel="nofollow">this</a>. In Developing a Device Administration Application section it gives the text below for the manifest.xml file.</p>

<pre><code>&lt;activity android:name=".app.DeviceAdminSample"
            android:label="@string/activity_sample_device_admin"&gt;
    &lt;intent-filter&gt;
        &lt;action android:name="android.intent.action.MAIN" /&gt;
        &lt;category android:name="android.intent.category.SAMPLE_CODE" /&gt;
    &lt;/intent-filter&gt;
&lt;/activity&gt;
&lt;receiver android:name=".app.DeviceAdminSample$DeviceAdminSampleReceiver"
        android:label="@string/sample_device_admin"
        android:description="@string/sample_device_admin_description"
        android:permission="android.permission.BIND_DEVICE_ADMIN"&gt;
    &lt;meta-data android:name="android.app.device_admin"
            android:resource="@xml/device_admin_sample" /&gt;
    &lt;intent-filter&gt;
        &lt;action android:name="android.app.action.DEVICE_ADMIN_ENABLED" /&gt;
    &lt;/intent-filter&gt;
&lt;/receiver&gt;
</code></pre>

<p><strong>The question</strong></p>

<p>What is '.app.DeviceAdminSample$DeviceAdminSampleReceiver' and what is dollar sign in middle of it? 
I'd read some other questions about dollar sign in java but i think mine is a bit different with them.</p>