Android Project Throwing io.jsonwebtoken.lang.UnknownClassException

I’ve setup my project according to the directions. My build.gradle is essentially the following:

dependencies {
    implementation fileTree(dir:'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.61"
    implementation "com.auth0.android:jwtdecode:1.4.0"
    implementation "com.google.code.gson:gson:2.8.6"

    testImplementation 'junit:junit:4.13'
    testImplementation "io.mockk:mockk:1.10.0"
    api 'io.jsonwebtoken:jjwt-api:0.11.2'
    runtimeOnly 'io.jsonwebtoken:jjwt-impl:0.11.2'
    runtimeOnly('io.jsonwebtoken:jjwt-orgjson:0.11.2') {
        exclude group: 'org.json', module: 'json' //provided by Android natively
    }

}

I am only trying to use this library to generate a JWT in the proper format so that I can unit test my JWT parser. I’ve created an incredibly simple function to generate the JWT:

    private fun createJwtToken(): String {
        val key: Key = Keys.secretKeyFor(SignatureAlgorithm.HS256)
        return Jwts.builder().setSubject("Joe").signWith(key).compact()
}

However, I get the following crash the moment that I run my unit test:

java.lang.IllegalStateException: Unable to invoke class method io.jsonwebtoken.impl.crypto.MacProvider#generateKey.  Ensure the necessary implementation is in the runtime classpath.

	at io.jsonwebtoken.lang.Classes.invokeStatic(Classes.java:202)
	at io.jsonwebtoken.security.Keys.secretKeyFor(Keys.java:136)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
Caused by: io.jsonwebtoken.lang.UnknownClassException: Unable to load class named [io.jsonwebtoken.impl.crypto.MacProvider] from the thread context, current, or system/application ClassLoaders.  All heuristics have been exhausted.  Class could not be found.  Have you remembered to include the jjwt-impl.jar in your runtime classpath?
	at io.jsonwebtoken.lang.Classes.forName(Classes.java:92)
	at io.jsonwebtoken.lang.Classes.invokeStatic(Classes.java:195)
	... 29 more

Everywhere that I’ve looked regarding this issue, the solution seems to always be that I need to ensure I’ve setup my Gradle dependencies correctly. However, I feel that I’ve done that and I’m still running into issues. Please let me know if additional information is needed.

[mikepalarz]

Understandable @lhazlewood , thanks for the feedback. I do agree that this was likely due to my particular environment in some way.

[lhazlewood]

@mikepalarz thanks for the update. Based on this, I’ll close this issue as it seems highly likely this is based on your local environment. If not and you find otherwise - no worries! I’m happy to re-open this issue!