title: CardView and other elements are not being displayed in my xml file
body: <p>I am using an <code>AppCompatActivity</code> and at the moment, I am trying to add a navigational drawer to the toolbar.</p>
  
  <p>Problem is, now the cardview is not being displayed and the navigational drawer is also not working.</p>
  
  <p>This is my code:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.v4.widget.DrawerLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="150dp"&gt;
  
      &lt;android.support.v7.widget.CardView
          xmlns:card_view="http://schemas.android.com/apk/res-auto"
          android:id="@+id/cards"
          android:layout_gravity="center"
          android:layout_width="match_parent"
          android:layout_height="200dp"
          card_view:cardCornerRadius="4dp"&gt;
          &lt;RelativeLayout
              android:layout_width="wrap_content"
              android:layout_height="match_parent"
              android:padding="10dp"
              android:layout_alignParentBottom="true"&gt;
  
              &lt;TextView
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:textAppearance="?android:attr/textAppearanceLarge"
                  android:text="Username"
                  android:id="@+id/usersName"
                  android:layout_alignParentTop="true"
                  android:layout_alignParentStart="true"
                  android:layout_alignParentEnd="true" /&gt;
  
              &lt;TextView
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:textAppearance="?android:attr/textAppearanceMedium"
                  android:text="Others"
                  android:id="@+id/others"
                  android:layout_centerVertical="true"
                  android:layout_alignParentStart="true" /&gt;
  
          &lt;/RelativeLayout&gt;
      &lt;/android.support.v7.widget.CardView&gt;
      &lt;android.support.design.widget.NavigationView
          android:layout_width="wrap_content"
          android:layout_height="match_parent"&gt;&lt;/android.support.design.widget.NavigationView&gt;
  &lt;/android.support.v4.widget.DrawerLayout&gt;
  </code></pre>
  
  <p>Would really mean a lot and make my day if someone could fix my error please. I don't know where I have gone wrong, and I just want to have the navigation drawer button in the toolbar and the cardview on the screen</p>