使用 Android 8 中的 Shape Drawable 设置按钮的背景颜色和边框颜色

Question

I am trying to set background color and border color of Button using Shape Drawable (create button_start.xml in drawable) in Android 8, but it does not seem to work.

button_start.xml file:

activity_main.xml file:

result:

Answer 1

Short answer: .
You don't need to define a background shape, just use a MaterialButton with the shapeAppearanceOverlay attribute:

        <com.google.android.material.button.MaterialButton
            android:layout_width="100dp"
            android:layout_height="100dp"
            style="@style/Widget.MaterialComponents.Button"
            app:backgroundTint="@color/...."
            app:strokeColor="@color/...."
            app:strokeWidth="5dp"
            android:padding="0dp"
            android:insetLeft="0dp"
            android:insetTop="0dp"
            android:insetRight="0dp"
            android:insetBottom="0dp"
            android:text="BUTTON"
            app:shapeAppearanceOverlay="@style/ShapeAppearanceOverlay.MyApp.Button.Circle"
            />

with:

<style name="ShapeAppearanceOverlay.MyApp.Button.Circle" parent="">
    <item name="cornerFamily">rounded</item>
    <item name="cornerSize">50%</item>
</style>

---

Long answer:
If you want to use a background shape you have to add app:backgroundTint="@null" .
Something like:

<Button
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:background="@drawable/shape_oval"
    app:backgroundTint="@null"

Using a Material Components Theme the Button is replaced at runtime by a MaterialButton which use a own MaterialShapeDrawable as background. You can define a custom background but to avoid that the custom background doesn't get tinted you have to add app:backgroundTint="@null" .
The 2 solutions are not equivalent.
Using a custom android:background the default MaterialShapeDrawable is not used and some features like stroke, shapeappearance, ripple are not set (since they are related to the MaterialShapeDrawable ). You have to provide them with your custom background.