title: Android Studio: Bottom Navigation View - AAPT: error: ' ' is incompatible with attribute drawable (attr) reference
body: <p>I have added BottomNavigationView in my application like.</p>
  
  <p><strong>main.xml</strong></p>
  
  <pre><code>&lt;com.google.android.material.bottomnavigation.BottomNavigationView
      android:layout_width="match_parent"
      android:layout_height="56dp"
      app:itemBackground="@drawable/nav_bgcolor"
      app:itemIconSize="50dp"
      app:itemIconTint="@color/nav_item_colors"
      app:itemTextColor="@color/nav_item_colors"
      app:labelVisibilityMode="unlabeled"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:menu="@menu/nav_items"&gt;
  &lt;/com.google.android.material.bottomnavigation.BottomNavigationView&gt;
  </code></pre>
  
  <p><strong>menu/nav_items.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  
  &lt;menu xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  
      &lt;item
          android:id="@+id/nav_home"
          android:icon="@drawable/home_white"
          android:title="@string/nav_home" /&gt;
      &lt;item
          android:id="@+id/nav_market"
          android:icon="@drawable/market_white"
          android:title="@string/nav_market" /&gt;
      &lt;item
          android:id="@+id/nav_news"
          android:icon="@drawable/news_white"
          android:title="@string/nav_news" /&gt;
      &lt;item
          android:id="@+id/nav_account"
          android:icon="@drawable/account_white"
          android:title="@string/nav_account" /&gt;
  &lt;/menu&gt;
  </code></pre>
  
  <p><strong>drawable/nav_bgcolor.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item android:drawable="#FF9800" android:state_checked="true" /&gt;
      &lt;item android:drawable="#FFFFFF" android:state_checked="false" /&gt;
  &lt;/selector&gt;
  </code></pre>
  
  <p><strong>color/nav_item_colors.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item android:color="#FFFFFF" android:state_checked="true"/&gt;
      &lt;item android:color="#727272"/&gt;
  &lt;/selector&gt;
  </code></pre>
  
  <p>this is the preview in the android studio</p>
  
  <p><a href="https://drive.google.com/file/d/1yICxFcTbSxYpILDtxg75Z4x-2Y1UaPM_/view?usp=sharing" rel="nofollow noreferrer">https://drive.google.com/file/d/1yICxFcTbSxYpILDtxg75Z4x-2Y1UaPM_/view?usp=sharing</a></p>
  
  <p>it is actually displaying the design that i want to happen.</p>
  
  <p>there is no error or something but when i run the app there are errors in <strong>drawable/nav_bgcolor.xml</strong></p>
  
  <pre><code>C:\Users\[PCNAME]\AndroidStudioProjects\[APPNAME]\app\src\main\res\drawable\nav_bgcolor.xml:3: AAPT: error: '#FF9800' is incompatible with attribute drawable (attr) reference.
  C:\Users\[PCNAME]\AndroidStudioProjects\[APPNAME]\app\src\main\res\drawable\nav_bgcolor.xml:4: AAPT: error: '#ffffff' is incompatible with attribute drawable (attr) reference.
  </code></pre>
  
  <p>the error happened after i added <strong>app:itemBackground="@drawable/nav_bgcolor"</strong> in the <strong>main.xml</strong></p>
  
  <p>I have searched the internet but no luck in getting any solution.</p>