Android's elevation property, designed to create shadows and visually distinguish UI elements, sometimes fails to function as expected. This is a common frustration for Android developers, especially when targeting different devices and API levels. Several factors can contribute to this issue, and troubleshooting often involves a process of elimination.

Common Causes and Solutions

1. Incorrect View Type: Elevation primarily works with View instances that are rendered in a 2D plane. Elements like TextView, ImageView, and custom View classes should generally support elevation. However, attempting to apply elevation to a container like LinearLayout might not yield the desired result, or might only cast a shadow for the entire container, not individual child views. Consider using a CardView or a MaterialCardView to wrap the element you want to elevate. These widgets are specifically designed for elevation and shadow casting.
2. Conflicting Background: The view needs a background to cast a shadow. If the view's background is transparent, elevation will have no visible effect. Ensure the view has a solid background color or a drawable resource. You can set this programmatically using view.setBackgroundColor(Color.WHITE) or through XML using the android:background attribute.
3. API Level Compatibility: Elevation was significantly improved and became more reliable starting with Android 5.0 (API Level 21). While the elevation attribute exists in earlier versions, the shadow implementation was often inconsistent and unreliable. If targeting older API levels, consider using shadow libraries like NineOldAndroids or custom drawable implementations for consistent shadow effects across devices.
4. Z-Ordering Issues: If another view overlaps the elevated view, the shadow might be obscured. Ensure the elevated view has a higher Z-order than overlapping views. You can manipulate Z-ordering using View.setZ(float) or through XML using android:translationZ. Also, check if the parent view has android:clipChildren="false". If set to false, child views can draw outside their parent's bounds, potentially obscuring the shadow.
5. Parent Clipping: The parent view might be clipping the shadow. By default, a view's content is clipped to its bounds. If the shadow extends beyond the view's boundaries and the parent clips its children, the shadow will be cut off. To prevent this, set android:clipChildren="false" on the parent layout. This allows child views to draw outside their parent's bounds.
6. Hardware Acceleration: Ensure hardware acceleration is enabled in your application. Hardware acceleration is generally enabled by default, but it's possible to disable it at the application, activity, or view level. Check your manifest file (android:hardwareAccelerated="true") and activity declarations to confirm that hardware acceleration is enabled.
7. Shadow Color and Opacity: While uncommon, sometimes the shadow is present but invisible due to a very light or transparent shadow color. Check your theme or style definitions for any overrides that might be affecting shadow colors.

Debugging Tips

• Inspect Layout Hierarchy: Use Android Studio's Layout Inspector to examine the view hierarchy and identify any overlapping views or unexpected clipping.
• Simplify the Layout: Temporarily remove unrelated views to isolate the elevated view and determine if other elements are interfering.
• Test on Different Devices and Emulators: Elevation behavior can vary across devices and Android versions. Test on a range of devices to identify any device-specific issues.

By systematically investigating these potential causes, you can usually pinpoint the reason why elevation isn't working as expected and implement the necessary corrections.

1080×1920 xml android navigation view items elevation stack overflow from stackoverflow.com