AndroidX迁移构建报错：Program type already present问题求助

Hey there! Let's tackle that duplicate class error you're hitting while migrating to AndroidX. This is a super common issue when mixing old Support Library dependencies with AndroidX, so let's break down the fixes step by step.

What's causing this? #

The error tells you that the same class exists in both your AndroidX dependencies and the old Support Library. This happens because some of your third-party libraries are still pulling in old Support Library code, which clashes with AndroidX's equivalent classes.

The main culprits in your setup: #

1. Outdated build tools: Your Android Gradle Plugin (3.1.2) and Kotlin (1.2.41) versions are too old—they don't have full support for AndroidX, which was introduced in newer tooling.
2. Unmigrated third-party libraries:
   • com.theartofdev.edmodo:android-image-cropper:2.7.0 uses old Support Library code instead of AndroidX.
   • Your Firebase dependencies (15.0.2) are outdated and likely pull in old Support Library classes.

Step-by-Step Solutions #

1. Update Your Build Tools & Kotlin Version #

First, we need to get your tooling up to speed to support AndroidX properly:

• Open your project-level build.gradle and update these dependencies:

  dependencies {
      classpath 'com.android.tools.build:gradle:3.6.4' // Stable version with full AndroidX support
      classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.72" // Compatible Kotlin version
      classpath 'com.google.gms:google-services:4.3.10' // Updated for Firebase compatibility
  }
  

• In your app-level build.gradle, make sure the kotlin_version variable matches the plugin version above (e.g., ext.kotlin_version = '1.3.72').

2. Replace Unmigrated Third-Party Libraries #

Swap out the libraries that are still using old Support Library code:

• Image Cropper: Replace the old version with an AndroidX-compatible release:

  implementation 'com.theartofdev.edmodo:android-image-cropper:4.3.0'
  

• Firebase: Upgrade to newer versions that support AndroidX:

  implementation 'com.google.firebase:firebase-messaging:23.0.0'
  implementation 'com.google.firebase:firebase-core:21.1.1'
  

3. Enable Jetifier to Auto-Migrate Dependencies #

Jetifier is a tool that automatically converts old Support Library references in third-party dependencies to AndroidX. Add these lines to your project-level gradle.properties:

android.useAndroidX=true
android.enableJetifier=true

This ensures even if a library hasn't been fully migrated, its old Support code gets swapped for AndroidX equivalents.

4. Clean & Rebuild Your Project #

Finally, clear any cached build files and rebuild:

• In Android Studio: Go to Build > Clean Project, then Build > Rebuild Project.
• Or run this in your terminal:

  ./gradlew clean build
  

If You Still Have Issues #

If the error persists, run this command to generate a dependency tree and track down any remaining old Support Library references:

./gradlew app:dependencies

Look for any entries under com.android.support:support-v4, then exclude that dependency from the problematic library. For example:

implementation('offending-library') {
    exclude group: 'com.android.support', module: 'support-v4'
}

内容的提问来源于stack exchange，提问作者sk panchal