Pros of Guice

• More actively maintained and widely adopted in the Java community
• Extensive documentation and community support
• Seamless integration with other Google libraries and frameworks

Cons of Guice

• Steeper learning curve for beginners
• Can lead to increased complexity in large projects
• Potential performance overhead due to runtime dependency resolution

Code Comparison

Guice:

public class BillingModule extends AbstractModule {
  @Override 
  protected void configure() {
    bind(TransactionLog.class).to(DatabaseTransactionLog.class);
    bind(CreditCardProcessor.class).to(PaypalCreditCardProcessor.class);
  }
}

Inject:

public class BillingModule extends AbstractModule {
  @Override
  public void configure() {
    bind(TransactionLog.class).to(DatabaseTransactionLog.class);
    bind(CreditCardProcessor.class).to(PaypalCreditCardProcessor.class);
  }
}

Both frameworks use similar syntax for dependency injection configuration, with minor differences in method signatures and class inheritance. Guice tends to offer more advanced features and annotations for complex scenarios, while Inject focuses on simplicity and ease of use.

Pros of Spring Framework

• Comprehensive ecosystem with extensive documentation and community support
• Modular architecture allowing for flexible adoption of specific components
• Robust integration with various technologies and frameworks

Cons of Spring Framework

• Steeper learning curve due to its extensive feature set
• Potentially heavier footprint for simpler applications
• More complex configuration and setup compared to lightweight alternatives

Code Comparison

Spring Framework:

@Autowired
private UserService userService;

@GetMapping("/users")
public List<User> getUsers() {
    return userService.getAllUsers();
}

Inject:

@Inject
UserService userService;

public List<User> getUsers() {
    return userService.getAllUsers();
}

Spring Framework offers more built-in annotations and features for web development, while Inject focuses primarily on dependency injection. Spring's code often includes additional annotations for request mapping and other web-related functionalities.

Spring Framework is a full-featured application framework, whereas Inject is a lightweight dependency injection library. Spring provides a comprehensive solution for enterprise applications, while Inject offers a simpler approach for projects primarily needing dependency injection.

Pros of Dagger

• More active development and community support
• Better integration with Android development ecosystem
• Extensive documentation and learning resources

Cons of Dagger

• Steeper learning curve for beginners
• More complex setup and configuration
• Potentially slower compile times for large projects

Code Comparison

Inject:

public class RealCar implements Car {
  @Inject Engine engine;
  @Inject Seat driver;
  @Inject Seat passenger;
}

Dagger:

@Module
public class CarModule {
  @Provides
  Engine provideEngine() {
    return new Engine();
  }
  @Provides
  Seat provideSeat() {
    return new Seat();
  }
}

Key Differences

• Inject uses field injection, while Dagger promotes constructor injection
• Dagger requires more boilerplate code but offers greater flexibility
• Inject is simpler to set up, but Dagger provides more robust compile-time checks

Use Cases

• Inject: Smaller projects or those prioritizing simplicity
• Dagger: Larger, more complex applications, especially Android projects

Community and Support

Dagger has a larger and more active community, with regular updates and extensive third-party resources. Inject, being archived, has limited ongoing support.

Pros of Ninja

• Full-featured web framework with built-in routing, templating, and database integration
• Designed for rapid development with convention over configuration approach
• Active community and regular updates

Cons of Ninja

• Steeper learning curve due to more comprehensive feature set
• Potentially heavier footprint for simple applications
• Less flexibility for custom dependency injection configurations

Code Comparison

Ninja (route definition):

public class ApplicationController {
    @GET("/hello/{name}")
    public Result hello(@PathParam("name") String name) {
        return Results.html().render("name", name);
    }
}

Inject (dependency injection):

public class RealBillingService implements BillingService {
    @Inject
    public RealBillingService(CreditCardProcessor processor,
                              TransactionLog transactionLog) {
        // ...
    }
}

Summary

Ninja is a comprehensive web framework offering a wide range of features for building web applications, while Inject focuses solely on dependency injection. Ninja provides a more opinionated structure and faster development for full-stack applications, but may be overkill for simpler projects. Inject offers more flexibility in dependency management but requires additional components for a complete web application stack.

Pros of Auto

• More actively maintained and updated
• Broader scope with multiple code generation tools
• Better integration with modern Java features and annotations

Cons of Auto

• Steeper learning curve due to more complex API
• Requires more configuration and setup for some use cases
• May generate more code than necessary in certain scenarios

Code Comparison

Inject:

public class RealCar implements Car {
  @Inject Engine engine;
  @Inject Seat driver;
  @Inject Seat passenger;
}

Auto:

@AutoValue
public abstract class Car {
  public abstract Engine engine();
  public abstract ImmutableList<Seat> seats();

  public static Builder builder() {
    return new AutoValue_Car.Builder();
  }

  @AutoValue.Builder
  public abstract static class Builder {
    public abstract Builder engine(Engine engine);
    public abstract Builder seats(ImmutableList<Seat> seats);
    public abstract Car build();
  }
}

Summary

Auto offers a more comprehensive set of code generation tools and better integration with modern Java features, but it may require more setup and generate more code in some cases. Inject focuses primarily on dependency injection with a simpler API, but it's less actively maintained. The choice between the two depends on specific project requirements and the desired level of code generation and dependency management.