Coding⏱️ 2 min read📅 2026-05-31

How to Fix: How to resolve NoClassDefFoundError: Failed resolution of: Landroid/view/View$OnUnhandledKeyEventListener;

Resolve NoClassDefFoundError: Failed resolution of Landroid/view/View$OnUnhandledKeyEventListener; in Android Studio 3.2.

Quick Answer: Check the AndroidX version in your project. Ensure it is compatible with the target SDK.

The NoClassDefFoundError: Failed resolution of Landroid/view/View$OnUnhandledKeyEventListener; exception is typically caused by a missing or outdated dependency in your project's build.gradle file. This error occurs when the Android Runtime (ART) cannot find the View.OnUnhandledKeyEventListener interface at runtime.

🛑 Root Causes of the Error

  • Missing or outdated dependency in build.gradle file.

🛠️ Step-by-Step Verified Fixes

Method 1: Update Gradle Dependency

  1. Step 1: Open the build.gradle file in your project and add the following dependency to the dependencies block:
dependencies { implementation 'androidx.appcompat:appcompat:29.0.2' }

Step 2:

  1. Step 2: Sync Gradle, Clean, and Build your project to ensure the changes are applied.

Method 2: Use AndroidX

  1. Step 1: Add the following code to your build.gradle file under the android block:
android { compileSdkVersion 29 targetSdkVersion 29 defaultConfig { javaCompileOptions.annotationProcessorOptions { enableSupportLibraryAnnotationProcessor = true } }

Step 2:

  1. Step 2: Sync Gradle, Clean, and Build your project to ensure the changes are applied.

💡 Conclusion

By following these steps, you should be able to resolve the NoClassDefFoundError: Failed resolution of Landroid/view/View$OnUnhandledKeyEventListener; exception in your Android project.

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