Lollipop's backgroundTint has no effect on a Button

The bad news

Like BoD says, it's meaningless to tint a Button's background in Lollipop 5.0 (API level 21).

The good news

Lollipop 5.1 (API level 22) seems to have fixed this by changing btn_mtrl_default_shape.xml (among other files): https://android.googlesource.com/platform/frameworks/base/+/6dfa60f33ca6018959ebff1efde82db7d2aed1e3%5E!/#F0

The great news

The new support library (version 22.1+) adds backward-compatible tinting support to lots of components, including AppCompatButton!

Unfortunately, the android:backgroundTint property still doesn't work (maybe I'm doing something wrong) -- so you have to set the ColorStateList in code, using setSupportBackgroundTintList(). It'd be really nice to see android:backgroundTint supported in the future. Update: Marcio Granzotto commented that app:backgroundTint works on AppCompatButton! Note that it's app:, not android:, because it's in the app/library.

<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <AppCompatButton
        android:id="@+id/mybutton"
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:text="Testing, testing"
        app:backgroundTint="#ff00ff"/>

</LinearLayout>

Your activity will automatically inflate an AppCompatButton instead of the normal Button if you let it inherit from AppCompatActivity.

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        AppCompatButton v = (AppCompatButton) findViewById(R.id.mybutton);
        ColorStateList csl = new ColorStateList(new int[][]{new int[0]}, new int[]{0xffffcc00});
        v.setSupportBackgroundTintList(csl);
    }
}

You should of course get the ColorStateList from a color resource, but I was lazy, so...

^{_{Oh, and don't forget to base your app theme on one of the Theme.AppCompat themes, or the compat views will be very, very sad... ;)}}

This worked on both 2.3.7 (Gingerbread MR1) and 5.0 (Lollipop 'Classic').

It seems that tinting a ripple drawable is meaningless (and the default background of a button is a ripple drawable).

In fact, after looking at the platform's default button drawable, I found the "correct" way to do this:. You have to define this in your theme:

    <item name="android:colorButtonNormal">@color/accent</item>

(Of course this is only for level 21+.)

Warning: since this is defined in a theme, this will use the given color for all the buttons (at least all of the buttons in activities using that theme.)

As a bonus, you can also change the ripple color by defining this:

    <item name="android:colorControlHighlight">@color/accent_ripple</item>

To resolve issues related to tinting on Android 5.0.x I use something like this:

public static void setButtonTint(Button button, ColorStateList tint) {
    if (Build.VERSION.SDK_INT == Build.VERSION_CODES.LOLLIPOP && button instanceof AppCompatButton) {
        ((AppCompatButton) button).setSupportBackgroundTintList(tint);
    } else {
        ViewCompat.setBackgroundTintList(button, tint);
    }
}

It uses the support method only for API 21 and the ViewCompat one for all other cases.