To set the color for Button can be used android:background=”color code” Button's
CEO: android:background=”#F00″ => me red.
However with this method when clicking the button we will not see the reaction it seemed Button should not click.

To fix this do the following:
Step 1: Create color.xml file in the folder res / values ​​with the following content (This file defines the colors to be used):

<?xml version="1.0" encoding="utf-8"?>
<resources>
     <color name="red">#f00</color>		<!-- Màu đỏ -->
     <color name="blue">#00f</color>	<!-- Màu xanh da trời -->
</resources>

Step 2: Create button_color.xml file in the folder res / drawable (without this folder, you can create new) with content (This file creates the color for button):

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/red" 	
        android:state_pressed="true"/>		<!-- Hiện màu đỏ khi ấn vào nút -->
    <item android:drawable="@color/blue" 
        android:state_pressed="false"/>		<!-- Hiện màu xanh da trời khi không nhấn nút -->
</selector>

Step 3: Use the command android:background=”@drawable/button_color” to put color in button_color file created

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:gravity="center">
    <LinearLayout 
        android:layout_width="fill_parent"
	    android:layout_height="wrap_content"
	    android:gravity="center">
        <TextView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="30sp"
            android:text="My Button"/>
    </LinearLayout>
    
    <LinearLayout 
        android:layout_width="fill_parent"
	    android:layout_height="wrap_content"
	    android:gravity="center"
	    android:layout_marginTop="20dp">

        <Button
            android:id="@+id/ok"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"            
            android:text="Click"
            android:textSize="30sp" 
            android:background="@drawable/button_color"/> <!-- Đặt màu trong file button_color -->

    </LinearLayout>
    
</LinearLayout>