# swagger-codegen > Generate code and documentation for your REST api from a OpenAPI/swagger definition. > More information: . - Generate documentation and code from an OpenAPI/swagger file: `swagger-codegen generate -i {{swagger_file}} -l {{language}}` - Generate Java code using the library retrofit2 and the option useRxJava2: `swagger-codegen generate -i {{http://petstore.swagger.io/v2/swagger.json}} -l {{java}} --library {{retrofit2}} -D{{useRxJava2}}={{true}}` - List available languages: `swagger-codegen langs` - Display help options for the generate command: `swagger-codegen help {{generate}}`