title: Cannot change the colour of the button of my android application in Android studio
body: <p>I'm new to android studio. I started to create a mobile application. I need to add a white color button to my mobile application. I just drag and drop a button and it shows as blue color in the Android studio design as well as in my phone. After I created a <code>button.xml</code> to change the color of the button. But still not fixed that problem.</p>
  <ul>
  <li>My phone is : <strong>Samsung M21</strong></li>
  <li>Android studio version: <strong>2020.3.1 Patch 3</strong></li>
  </ul>
  <p>I will add my code of the button and screenshots of the android design as well as in my phone.</p>
  <p>This is the problem I have.</p>
  <p>This screenshot is in the Android Design.</p>
  <p><a href="https://i.stack.imgur.com/t7saF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/t7saF.png" alt="enter image description here" /></a></p>
  <p>This screenshot is on my mobile phone.</p>
  <p><a href="https://i.stack.imgur.com/gWyme.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gWyme.jpg" alt="enter image description here" /></a></p>
  <p><strong>code of the button (activity_to_do.xml)</strong></p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
  &lt;androidx.constraintlayout.widget.ConstraintLayout xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
      xmlns:app=&quot;http://schemas.android.com/apk/res-auto&quot;
      xmlns:tools=&quot;http://schemas.android.com/tools&quot;
      android:layout_width=&quot;match_parent&quot;
      android:layout_height=&quot;match_parent&quot;
      tools:context=&quot;.todo.ToDo&quot;&gt;
  
      &lt;Button
          android:id=&quot;@+id/button&quot;
          android:layout_width=&quot;wrap_content&quot;
          android:layout_height=&quot;wrap_content&quot;
          android:text=&quot;Button&quot;
          android:background=&quot;@drawable/button&quot;
          app:layout_constraintBottom_toBottomOf=&quot;parent&quot;
          app:layout_constraintEnd_toEndOf=&quot;parent&quot;
          app:layout_constraintStart_toStartOf=&quot;parent&quot;
          app:layout_constraintTop_toTopOf=&quot;parent&quot; /&gt;
  
  &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  </code></pre>
  <p><strong>button.xml</strong></p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
  &lt;shape xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot; android:shape=&quot;rectangle&quot;&gt;
      &lt;corners android:radius=&quot;50px&quot;/&gt;
      &lt;solid android:color=&quot;@color/white&quot;/&gt;
  &lt;/shape&gt;
  </code></pre>
  <p>can anyone help me? I need to change the color of the button to white.</p>