Duplicated files copied in APK when including both Joda Time and Common IO libraries in Android project

Duplicated Files in APK: Joda Time and Commons IO

The Problem

When including both Joda Time and Apache Commons IO libraries in an Android project, you might encounter duplicated files within your APK. This happens because both libraries rely on the same underlying classes for file system interaction, leading to conflicts and increased APK size.

Root Cause: Conflicting Dependencies

The core issue lies in the dependency management of your project. Joda Time and Commons IO, while providing different functionalities, often depend on common libraries like:

• Apache Commons Lang: Offers utility classes for working with strings, arrays, and other Java objects.

Impact of Duplicate Files

• Increased APK size: Duplicated files directly contribute to a larger APK, slowing down downloads and increasing storage consumption.
• Potential runtime conflicts: In rare cases, having multiple versions of the same class can lead to unpredictable behavior at runtime.

Resolution: Dependency Management Techniques

1. Excluding Conflicting Dependencies

You can exclude the conflicting dependencies from either Joda Time or Commons IO by using dependency exclusion rules in your build file (usually build.gradle).

dependencies {
  // ... other dependencies
  implementation("joda-time:joda-time:2.10.14") {
    exclude group: 'commons-lang', module: 'commons-lang'
  }
  implementation("commons-io:commons-io:2.11") 
}

2. Using Dependency Version Management Tools

For complex projects with many dependencies, tools like Maven or Gradle help manage dependencies effectively:

• Maven: Provides a central repository and dependency management capabilities.
• Gradle: Widely used in Android projects, offers flexible dependency handling with exclusion and conflict resolution features.

3. Dependency Conflicts in Android Studio

Android Studio provides a handy feature to help resolve dependency conflicts. In the “External Libraries” section of the Project view, you can see all the dependencies and their versions. Double-clicking on a dependency opens a window where you can modify its configuration, including exclusion rules.

Comparison Table

Code Example

// Example using dependency exclusion
dependencies {
  implementation("joda-time:joda-time:2.10.14") {
    exclude group: 'commons-lang', module: 'commons-lang'
  }
  implementation("commons-io:commons-io:2.11") 
}

Conclusion

Avoiding duplicate files in APKs is crucial for optimal app performance and user experience. Understanding the root cause of such issues and applying proper dependency management techniques like dependency exclusion and using version management tools effectively can help resolve these conflicts and ensure a streamlined development process.