Android, setting background color of button loses ripple effect

You can add the ripple effect & background color with an additionnal ripple drawable:

your layout :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/button_connect"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dip"
        android:fontFamily="sans-serif"
        android:text="Connect"
        android:background="@drawable/ripple"
        android:textColor="#FFFFFF"
        android:textSize="18sp" />

</LinearLayout>

ripple.xml (this is where you can add background color in addition to the ripple effect) :

<?xml version="1.0" encoding="utf-8"?>
<!-- in drawable folder-->
<ripple
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="?android:colorControlHighlight">

    <item android:id="@android:id/mask">
        <shape android:shape="rectangle">
            <solid android:color="?android:colorAccent" />
        </shape>
    </item>

    <item>
        <shape android:shape="rectangle">
            <!-- put your background color here-->
            <solid android:color="@color/default_color" />
        </shape>
    </item>

</ripple>

Don't change the background of Button. Change the theme.

<style name="ButtonGray">
    <item name="colorButtonNormal">@color/gray</item>
</style>

and in your xml file

<Button
     android:id="@+id/accept_button"
     android:layout_height="wrap_content"
     android:layout_width="0dp"
     android:layout_weight="1"
     android:text="@string/button_accept_group"
     android:theme="@style/ButtonGray"/>

Or you can add it in your main app theme

<style name="AppTheme"
           parent="Theme.AppCompat.Light.NoActionBar">
        <item name="colorButtonNormal">@color/primary_color</item>
</style>

And don't need change button background.

If you want totally custom background you need create your selector. And you can set there ripple effect.

A very simple and straight forward way of doing this is to set ?attr/selectableItemBackground to android:foreground attribute of your button. Following xml is perfectly valid and works

<Button
    android:id="@+id/btn"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/white"
    android:foreground="?attr/selectableItemBackground"/>