Using api instead of implementation in build.gradle Dependencies

When working on an Android project, you may have come across the terms "API" and "Implementation" while adding dependencies to your app's build.gradle file. These two declarations are used to specify how a dependency should be included in your project, but their difference can sometimes be confusing. In this article, we will explain the difference between these two approaches and provide some guidance on when to use each one.

What is the Difference Between API and Implementation?

In general, both api and implementation are used to declare dependencies that your Android project needs to compile and run. However, there are some differences between the two:

• API: This declaration means that the module containing the dependency will be visible and accessible to all other modules in the project at both compile-time and runtime. The dependency is part of the public interface of the module, hence any module which uses this module will be able to see the dependency.
• Implementation: This declaration means that the dependency will only be visible to the module it has been declared in during compile-time. It will not be a part of the public interface of that module. This means that any module that depends on the current module will not be able to see this dependency.

In simple words, api makes the dependency available to the entire project, while implementation keeps it hidden for other modules.

When to Use API

You should use api when you want to expose the dependency as part of your module's public API. For example, if you are creating a library module that other developers can use, you might want to use api to make sure that the library's dependencies are also available to anyone who uses it.

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1// Example of using API
2dependencies {
3    api 'com.squareup.retrofit2:retrofit:2.9.0'
4}

Here, the Retrofit library is being added to the project as part of the public API. Any module that uses this library will be able to see the Retrofit classes and methods.

When to Use Implementation

On the other hand, you should use implementation when you want to keep the dependency private to a specific module. For instance, if you are creating an Android app that has multiple modules, each with its own dependencies, you would want to use implementation to ensure that these dependencies do not bleed into other modules.

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1// Example of using Implementation
2dependencies {
3    implementation 'com.squareup.okhttp3:okhttp:4.9.2'
4}

Here, the OkHttp library is being added to the module as a private dependency. Other modules cannot see it or access its classes and methods.

Conclusion

In conclusion, api and implementation are both used to declare the dependencies of your Android project, but with different visibility scopes. You should use api when you want to expose the dependency as part of your module's public API, and use implementation when you want to keep the dependency private to a specific module. By understanding the difference between these two types of dependencies, you can better manage your project's dependencies and avoid unexpected issues.