Swagger UI integration in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

Swagger UI Endpoint Accessibility

You have integrated Swagger UI in your Spring Boot application. After running the app, which URL will correctly display the Swagger UI page by default?

A http://localhost:8080/docs

B http://localhost:8080/swagger

C http://localhost:8080/swagger-ui.html

D http://localhost:8080/api-docs

💡 Hint

Swagger UI default path usually ends with .html

The default Swagger UI page in Spring Boot is accessible at /swagger-ui.html. Other paths like /api-docs or /swagger are not the default UI endpoints.

📝 Syntax

intermediate

Correct Swagger Configuration Bean

Which of the following code snippets correctly defines a Swagger configuration bean in Spring Boot using Springfox 3.x?

A

@Bean
public Docket api() {
    return new Docket(DocumentationType.OAS_30)
        .select()
        .apis(RequestHandlerSelectors.basePackage("com.example"))
        .paths(PathSelectors.any())
        .build();
}

B

@Bean
public SwaggerConfig api() {
    return new SwaggerConfig();
}

C

@Bean
public Docket api() {
    return new Docket(DocumentationType.SWAGGER_2)
        .select()
        .apis(RequestHandlerSelectors.any())
        .paths(PathSelectors.any())
        .build();
}

D

@Bean
public Docket api() {
    return new Docket(DocumentationType.SWAGGER_3)
        .select()
        .apis(RequestHandlerSelectors.any())
        .paths(PathSelectors.any())
        .build();
}

💡 Hint

Use the correct DocumentationType enum for OpenAPI 3.0 support

Springfox 3.x supports OpenAPI 3.0 using DocumentationType.OAS_30. Using SWAGGER_2 is for Swagger 2.0. SWAGGER_3 is not a valid enum.

🔧 Debug

advanced

Swagger UI Not Loading Static Resources

You added Swagger UI to your Spring Boot app, but the UI loads without styles and scripts, showing a broken page. What is the most likely cause?

A Swagger UI requires a separate server to serve static files

B Incorrect controller mapping for Swagger endpoints

C Missing dependency for springfox-swagger-ui in the build file

D Spring Security blocking access to Swagger static resources

💡 Hint

Check if security settings allow access to /swagger-ui/** and /v3/api-docs/**

Spring Security often blocks access to Swagger UI static resources unless explicitly permitted. Missing dependencies or controller mappings usually cause errors or no UI at all, not broken styles.

🧠 Conceptual

advanced

Purpose of @OpenAPIDefinition Annotation

What is the main purpose of the @OpenAPIDefinition annotation in a Spring Boot application using springdoc-openapi?

A To define global metadata like title, version, and description for the OpenAPI documentation

B To configure security schemes for API authentication

C To enable Swagger UI endpoint in the application

D To automatically generate REST controllers from OpenAPI specs

💡 Hint

Think about what metadata means for documentation

@OpenAPIDefinition is used to provide global information such as API title, version, and description in the OpenAPI docs. It does not enable UI or generate controllers.

❓ state_output

expert

Effect of Multiple Docket Beans on Swagger UI

In a Spring Boot app, you define two Docket beans with different group names: apiV1 and apiV2. What will the Swagger UI display when accessed at /swagger-ui.html?

A Only the apiV1 group APIs are shown by default

B A dropdown to select between apiV1 and apiV2 API groups

C An error because multiple Docket beans are not supported

D Swagger UI shows combined APIs from both groups without distinction

💡 Hint

Swagger UI supports multiple API groups via dropdown selection

When multiple Docket beans with different group names exist, Swagger UI shows a dropdown to select which API group to view. It does not error or merge groups automatically.