Java.lang.IllegalStateException: Ambiguous mapping. Cannot map Controller method

While defining spring rest endpoints you may encounter Java.lang.IllegalStateException: Ambiguous mapping. Cannot map Controller method error.

The most common reason for this error is that we have multiple APIs with the same URI and HTTP method.

The below code will throw Java.lang.IllegalStateException: Ambiguous mapping. Cannot map Controller method.

@RestController
@RequestMapping("/student")
public class StudentController {

    @Autowired
    private StudentService studentService;

    @Autowired
    private StudentRepository studentRepository;

    @PostMapping("/create")
    public Student createStudent1(@RequestBody Student student) {
        Student createResponse = studentService.save(student);
        return createResponse;
    }

    @PostMapping("/create")
    public Student updateStudent(@RequestBody Student student) {
        Student updateResponse = studentService.update(student);
        return updateResponse;
    }

}

Observe the above code snippet. We have two APIs with same URI http://localhost:9092/student/{name} and HTTP method i.e GET.

In order to fix this issue, we need to change URI or HTTP method.

Fixing by changing URI

@RestController
@RequestMapping("/student")
public class StudentController {

    @Autowired
    private StudentService studentService;

    @Autowired
    private StudentRepository studentRepository;

    @PostMapping("/create")
    public Student createStudent1(@RequestBody Student student) {
        Student createResponse = studentService.save(student);
        return createResponse;
    }

    @PostMapping("/update")
    public Student updateStudent(@RequestBody Student student) {
        Student updateResponse = studentService.update(student);
        return updateResponse;
    }

}

Fixing by changing HTTP method

We can define multiple rest endpoints with the same but make sure HTTP meth

@RestController
@RequestMapping("/student")
public class StudentController {

    @Autowired
    private StudentService studentService;

    @Autowired
    private StudentRepository studentRepository;

    @PostMapping("/create")
    public Student createStudent1(@RequestBody Student student) {
        Student createResponse = studentService.save(student);
        return createResponse;
    }

    @PutMapping("/create")
    public Student updateStudent(@RequestBody Student student) {
        Student updateResponse = studentService.update(student);
        return updateResponse;
    }

}

Did you notice? We have changed @PostMapping and @PutMapping but still, URI is the same.

Can we define multiple rest endpoints with the same name?

Yes, we can define it, but the HTTP method should be different,

Java.lang.IllegalStateException: Ambiguous mapping. Cannot map Controller method

Stacktrace for this exception

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘requestMappingHandlerMapping’ defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map ‘studentController’ method
com.javatute.controller.StudentController#createStudent1(Student)
to {POST /student/create}: There is already ‘studentController’ bean method
com.javatute.controller.StudentController#updateStudent(Student) mapped.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1796) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:893) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at com.javatute.main.SpringMain.main(SpringMain.java:13) [classes/:na]
Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map ‘studentController’ method
com.javatute.controller.StudentController#createStudent1(Student)
to {POST /student/create}: There is already ‘studentController’ bean method
com.javatute.controller.StudentController#updateStudent(Student) mapped.
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.validateMethodMapping(AbstractHandlerMethodMapping.java:636) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:603) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:318) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.registerHandlerMethod(RequestMappingHandlerMapping.java:378) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.registerHandlerMethod(RequestMappingHandlerMapping.java:75) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lambda$detectHandlerMethods$1(AbstractHandlerMethodMapping.java:288) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_251]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:286) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.processCandidateBean(AbstractHandlerMethodMapping.java:258) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:217) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:205) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:189) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
… 17 common frames omitted

That’s all about how to fix Java.lang.IllegalStateException: Ambiguous mapping. Cannot map Controller method error.

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