Android Studio XML context error
<p>Hi I'm following this Simple Parse Messaging App tutorial-<a href="https://github.com/codepath/android_guides/wiki/Building-Simple-Chat-Client-with-Parse" rel="nofollow">https://github.com/codepath/android_guides/wiki/Building-Simple-Chat-Client-with-Parse</a>
And I'm getting an error on this line of code: </p>

<pre><code>tools:context="${relativePackage}.${activityClass}" 
</code></pre>

<p>This is the whole file:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="${relativePackage}.${activityClass}" &gt;

&lt;EditText
    android:id="@+id/etMessage"
    android:layout_toLeftOf="@+id/btSend"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/btSend"
    android:gravity="top"
    android:hint="contribute..."
    android:imeOptions="actionSend"/&gt;
&lt;Button
    android:id="@+id/btSend"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center_vertical|right"
    android:paddingRight="10dp"
    android:layout_alignParentRight="true"
    android:text="send"
    android:textSize="18sp" &gt;
&lt;/Button&gt;

&lt;/RelativeLayout&gt;                                                                                   
</code></pre>