NumberFormatException: For input string: "" JSON conversion on x-example field

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We tried to upgrade to 2.9.2 from 2.8.0 and fond that there was an error appearing in the console when running the swagger UI end point.

This error report is for an exception that get’s thrown when there is no example attribute for an operation with an @ApiParam. When the param value is defined as an Integer or Long (or not a String). The code defaults the values to “” and this causes a NumberFormatException when attempting to convert to a number during JSON conversion in the springfox code.

I’ve created an example repo here.

https://github.com/andrew-dwp/springfox292bug.git

Steps: Download example repo (or create a spring boot program with a single end point that has a Long as an @ApiParam e.g.

    ResponseEntity<Person> getPerson(@RequestHeader(value = "sessionId") String sessionId,
                                     @ApiParam(value = "ID of person to return", required = true) @PathVariable("personId") Long personId);

Then hit the swagger UI http://localhost:8080/swagger-ui.html.

The error is:

java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_172]
	at java.lang.Long.parseLong(Long.java:601) ~[na:1.8.0_172]
	at java.lang.Long.valueOf(Long.java:803) ~[na:1.8.0_172]
	at io.swagger.models.parameters.AbstractSerializableParameter.getExample(AbstractSerializableParameter.java:412) ~[swagger-models-1.5.20.jar:1.5.20]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_172]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_172]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_172]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_172]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:664) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:633) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:536) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:30) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:292) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:3697) [jackson-databind-2.8.10.jar:2.8.10]
	at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3073) [jackson-databind-2.8.10.jar:2.8.10]
	at springfox.documentation.spring.web.json.JsonSerializer.toJson(JsonSerializer.java:38) [springfox-spring-web-2.9.2.jar:null]
	at springfox.documentation.swagger2.web.Swagger2Controller.getDocumentation(Swagger2Controller.java:105) [springfox-swagger2-2.9.2.jar:null]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_172]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_172]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_172]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_172]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) [spring-webmvc-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:108) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_172]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_172]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.27.jar:8.5.27]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_172]

[danny90zgz]

This error log is produced when swagger tries to render the swagger-ui.html becuase there is no provided example for the Long value personId field.

You can fix this by providing and example. Like this (, example = “123”):

ResponseEntity<Person> getPerson(@RequestHeader(value = "sessionId") String sessionId,
  @ApiParam(value = "ID of person to return", required = true, example = "123") @PathVariable("personId") Long personId);

[daddyrusher]

Hi, it helps me: Gradle Kotlin DSL:

implementation("io.springfox:springfox-swagger2:2.9.2") {
        exclude("io.swagger:swagger-models")
    } 
implementation("io.swagger:swagger-models:1.5.21")

Maven POM:

<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>2.9.2</version>
    <exclusions>
        <exclusion>
            <groupId>io.swagger</groupId>
            <artifactId>swagger-models</artifactId>
        </exclusion>
    </exclusions>
</dependency>

<!-- https://mvnrepository.com/artifact/io.swagger/swagger-models -->
<dependency>
    <groupId>io.swagger</groupId>
    <artifactId>swagger-models</artifactId>
    <version>1.5.21</version>
</dependency>

Good luck!