Cannot be cast to class because they are in unnamed module of loader 'app'

Question

I'm trying to create a bean from sources that were generated by wsdl2java.

Every time I try to run my Spring Boot app, I get the following error:

Caused by: java.lang.ClassCastException: class org.apache.cxf.endpoint.ClientImpl cannot be cast to class com.xignite.services.XigniteCurrenciesSoap (org.apache.cxf.endpoint.ClientImpl and com.xignite.services.XigniteCurrenciesSoap are in unnamed module of loader 'app')

I'm not sure how exactly I'm to include generated sources in my main Spring Boot application as a module.

My directory structure is:

├── build
│   └── generatedsources
│       └── src
│           └── main
│               └── java
│                   └── com
│                       └── xignite
│                           └── services
│      
└── src
    └── main
        ├── java
        │   └── io
        │       └── mateo
        │           └── stackoverflow
        │               └── soapconsumption
        └── resources
           └── wsdls

Relevant system info:

openjdk version "11.0.1" 2018-10-16
OpenJDK Runtime Environment 18.9 (build 11.0.1+13)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.1+13, mixed mode)

Spring Boot 2.1.2.RELEASE
Gradle 5.2

I've also uploaded the project onto Github here: https://github.com/ciscoo/soap-consumption-spring-boot

not very sure about wsdl here...but, did you try adding a module-info.java to your project and/or ensure that the module you're depending upon (for classes org.apache.cxf.endpoint.ClientImpl) is resolved on the modulepath rather than the classpath. — Naman
There is no “because” in the error message. All this addendum tells you, is, that both classes are located in the same module, the unnamed module of loader 'app', which helps the reader to understand that this problem is entirely unrelated to modules. ClientImpl simply is not a subtype of XigniteCurrenciesSoap; it's an ordinary ClassCastException. — Holger
In my case it was a little bit different. Class Cast Exception sometime happen because of the conflict between different version of the java. in pom.xml i set to use "<java.version>1.8</java.version> but in Intellje IDE i set to use java version 11. after changing java version from 11 to 8 problem solved for me. — Saman Salehi

orirab orirab · Accepted Answer · 2019-09-02T08:23:28

I had a similar case, and (as mentioned by @Holger in the comment) the module info in the message is simply misleading - this is an actual case of trying to cast something to something that doesn't match it.

In your case, ClientImpl simply is not a subtype of XigniteCurrenciesSoap.

Cannot be cast to class because they are in unnamed module of loader 'app'

2 Answers