Create XML into res/drawable/button.xml.
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="true" >
    <shape>
        <solid
            android:color="#343434" />
        <stroke
            android:width="1dp"
            android:color="#171717" />
        <corners
            android:radius="3dp" />
        <padding
            android:left="10dp"
            android:top="10dp"
            android:right="10dp"
            android:bottom="10dp" />
    </shape>
</item>
<item>
    <shape>
        <gradient
            android:startColor="#343434"
            android:endColor="#171717"
            android:angle="270" />
        <stroke
            android:width="1dp"
            android:color="#171717" />
        <corners
            android:radius="4dp" />
        <padding
            android:left="10dp"
            android:top="10dp"
            android:right="10dp"
            android:bottom="10dp" />
    </shape>
   </item>
</selector>
And set to your Button as Background like
  <Button
    android:id="@+id/btnValidate"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:background="@drawable/button"
    android:text="SOS Trasition"
    android:textColor="@android:color/white"
    android:textSize="16sp"
    android:textStyle="bold" />
And if you want Change  Button Text Color then create XML file at res/color/button_text.xml: 
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="true"
      android:color="#ffff0000"/> <!-- pressed -->
<item android:state_focused="true"
      android:color="#ff0000ff"/> <!-- focused -->
<item android:color="#ff000000"/> <!-- default -->
</selector>
And set this layout XML will apply the color list to a View: 
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/button_text"
android:textColor="@color/button_text" />