title: adding a click effect to my button in android
body: <p>i have made a custom  button for my layout but the problem is it doesnt show me a onclick effect.
  here are my three xml files that ive build
  i have given button  an oval shape can you also tell me how to make the button a circle and smaller in size??
  thnx in advance
      
      
      </p>
  
  <pre><code>&lt;TextView
      android:id="@+id/textView1"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:text="0"
      android:gravity="center"
      android:textSize="25sp" /&gt;
  
  &lt;Spinner 
      android:id="@+id/spin"
    android:gravity="center"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:spinnerMode="dropdown"
      android:text="heyyy"
      android:layout_below="@+id/textView1"
      /&gt;
  
  &lt;Button
      android:layout_marginTop="20dp"
      android:id="@+id/button1"
      android:layout_width="match_parent"
      android:layout_height="150sp"
      android:text="add"
      android:gravity="center" 
      android:layout_centerHorizontal="true"
       android:layout_below="@+id/spin"
       android:background="@drawable/button_xml"
       /&gt;
   &lt;TextView
      android:id="@+id/textView2"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView3"
    android:layout_below="@+id/button1"
      android:gravity="left"
      android:textSize="25sp"
      android:text="add" /&gt;
  
    &lt;TextView
      android:id="@+id/textView3"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
    android:layout_below="@+id/button1"
      android:gravity="right"
      android:textSize="25sp"
       android:text="a" /&gt;
     &lt;Button
      android:layout_marginTop="20dp"
      android:id="@+id/button2"
      android:layout_width="match_parent"
      android:layout_height="50sp"
      android:text="reset"
      android:gravity="center" 
      android:layout_centerHorizontal="true"
       android:layout_below="@+id/textView3"/&gt;
  
  &lt;/RelativeLayout&gt;
  &lt;/ScrollView&gt;
  </code></pre>
  
  <p>button_xml.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;shape xmlns:android="http://schemas.android.com/apk/res/android" 
  android:shape="oval"
  
  &gt;
  &lt;solid 
  android:color="#03A89E"/&gt;
  &lt;stroke android:width="2dp" 
          android:color="#ffffff"/&gt;
  
  &lt;/shape&gt;
  </code></pre>
  
  <p>button_click.xml</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:state_pressed="true"
      android:drawable="@drawable/button_xml"
      /&gt;
  &lt;/selector&gt;
  </code></pre>