升级Android Support Library至27.0.2后CardView属性丢失问题求助

Hey there, let’s tackle your issues step by step—both the missing CardView attributes and the Lint vs SDK Tools version mismatch.

1. Why are CardView attributes missing after upgrading to 27.0.2, and how to fix it? #

The error where cardBackgroundColor, cardCornerRadius, and contentPadding aren’t found is almost always related to dependency synchronization issues or inconsistent library versions, not a breaking change in the Support Library itself (these attributes are still supported in 27.0.2). Here are the most effective fixes:

• Ensure all Support Library dependencies use the same version
  Mixing versions (e.g., using appcompat-v7:27.0.1 with cardview-v7:27.0.2) can cause conflicts. Open your module-level build.gradle and make sure every com.android.support: entry uses 27.0.2. For example:

  dependencies {
      implementation 'com.android.support:appcompat-v7:27.0.2'
      implementation 'com.android.support:cardview-v7:27.0.2'
      // Other support libraries should match this version too
  }
  

• Clean and rebuild your project
  AAPT (Android Asset Packaging Tool) often caches old resource definitions. Go to Build > Clean Project, then Build > Rebuild Project in Android Studio. If you prefer command line, run:

  ./gradlew clean build
  

• Clear Gradle caches
  Corrupted Gradle caches can lead to sync issues. Delete the .gradle folder in your project’s root directory, plus the global Gradle cache (located at ~/.gradle/caches on Mac/Linux or C:\Users\<YourName>\.gradle\caches on Windows). Then re-sync your project with File > Sync Project with Gradle Files.

• Double-check your XML namespace
  While your existing XML looks correct, confirm the namespace declaration is still valid:

  xmlns:card_view="http://schemas.android.com/apk/res-auto"
  

  Sometimes typos or IDE glitches can break this, though it’s less likely since 27.0.1 worked fine.

2. Is Lint wrong for suggesting 27.0.2 when SDK Platform/Tools are at 27.0.1? #

Nope, this isn’t a Lint bug—here’s why:

• The Android Support Library and SDK Platform/Platform-Tools are separate components with independent versioning. Support Library updates often roll out faster than SDK Platform updates, as they focus on bug fixes, new features, and compatibility improvements without requiring a full platform update.
• Lint is correctly pointing to the latest available version of the Support Library (27.0.2), which is fully compatible with SDK Platform 27.0.1. You don’t need to wait for an SDK Platform update to use the newer Support Library version.

You can safely remove the //noinspection GradleDependency comment once you’ve fixed the attribute issue.

内容的提问来源于stack exchange，提问作者Gerard Frijters