升级Gradle至4.4后构建APK报错：废弃API与主Dex列表生成失败

Hey there, let's tackle these two linked issues you're facing after upgrading Gradle to 4.4. Both the deprecated API warnings and the multidex build failure can be resolved with targeted steps—let's break it down:

1. First: Get Details on Deprecated APIs #

The "Some input files use or override a deprecated API" warning means parts of your code (or dependencies) are relying on outdated Android/Java APIs. To see exactly which classes or methods are problematic, add the -Xlint:deprecation compiler argument to your app-level build.gradle to force detailed warnings:

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
        // Add this line to show full deprecation details in build logs
        compilerArgs << "-Xlint:deprecation"
    }

    // Optional: Make deprecation warnings more prominent
    lintOptions {
        warning 'deprecation'
        // Uncomment below if you want to enforce fixing deprecations by treating them as errors
        // error 'deprecation'
    }
}

Rebuild your project, and the log will now show specific lines of code (or dependency classes) using deprecated APIs. Replace those with modern alternatives—this might even resolve the multidex issue indirectly, as outdated code can sometimes cause dex list generation glitches.

2. Fix the Multidex List Generation Failure #

The TransformException: Error while generating the main dex list error usually comes from misconfigured multidex, cached build artifacts, or dependency conflicts. Try these fixes in order:

• Verify Multidex Configuration (if your minSdkVersion is < 21):
  Enable multidex in your app-level build.gradle:

  android {
      defaultConfig {
          // ... other existing configs
          minSdkVersion 19 // Example: any version below 21
          multiDexEnabled true
      }
  }
  
  dependencies {
      // Use this for non-AndroidX projects
      implementation 'com.android.support:multidex:1.0.3'
      // For AndroidX projects, use this instead:
      // implementation 'androidx.multidex:multidex:2.0.1'
  }
  

  Then update your Application class:

  • Either extend MultiDexApplication:

    public class MyApp extends MultiDexApplication {
        // ... your app's existing logic
    }
    

  • Or if you can't extend MultiDexApplication, add this to your existing Application class:

    @Override
    protected void attachBaseContext(Context base) {
        super.attachBaseContext(base);
        MultiDex.install(this);
    }
    

  Don't forget to reference your custom Application class in AndroidManifest.xml if you haven't already.

• Clean Build Artifacts
  Cached files often cause weird multidex issues. Run these commands in your project root:

  ./gradlew clean
  ./gradlew assembleDebug
  

  Alternatively, in Android Studio, go to File > Invalidate Caches / Restart and select "Invalidate and Restart".

• Check for Dependency Conflicts
  Duplicate or conflicting dependencies can break dex list generation. Generate a dependency tree to spot issues:

  ./gradlew app:dependencies
  

  Look for duplicate libraries (e.g., multiple versions of support libraries) and exclude duplicates using exclude group: 'com.example', module: 'conflicting-library' in your dependency declarations.

• Ensure Gradle Plugin Compatibility
  Gradle 4.4 is designed to work with Android Gradle Plugin (AGP) version 3.1.x. Verify your project-level build.gradle uses a compatible AGP version:

  buildscript {
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.1.4' // Matches Gradle 4.4
      }
  }
  

• Customize Multidex Keep Rules (If Needed)
  If certain classes must be included in the main dex file (e.g., Application class, startup dependencies), create a multidex-config.txt file in your app module root with lines like:

  com/yourpackage/MyApp.class
  com/yourpackage/important/StartupClass.class
  

  Then reference it in your app-level build.gradle:

  android {
      buildTypes {
          debug {
              multiDexKeepFile file('multidex-config.txt')
          }
      }
  }
  

Final Notes #

Start by fixing the deprecated API issues first—resolving those often clears up underlying build inconsistencies. If the multidex error persists after that, work through the multidex configuration and cache steps above.

内容的提问来源于stack exchange，提问作者Mukesh Makavana