Learning Java 8 Streams

I’ve never had a good opportunity to use Java 8 Streams since traditional iteration approaches always seemed to be appropriate for what I needed. Working on my Sudoku related projects (in particular an implementation of a Human Solver) I needed an approach to count occurrences of numbers in Lists and also find where pairs existed in Lists.

To get started, I started with a number of simpler examples to gradually work up to what I was looking for. I’ve collected a number of my examples in this project here.

Revisiting my spotviz.info webapp: visualizing WSJT-X FT8 spots over time – part 2: jaxb with Java 9 and beyond

Continuing from my efforts to get my SpotViz.info site up and running again on a current version of WildFly before refreshing the tech used to run the app, I ran into the first major issue: jaxb and support on Java 9 and beyond.

This is the first time I’ve run into this in practice, but was aware of the move to remove jaxb from Java SE in releases after Java 9. Deploying and running the app locally on WildFly17 and Java 8 everything deploys and works unchanged, but now I’m deploying to a test Ubuntu18.04 server in a VM on my local rack server before moving to the cloud, I’m running into all sorts of exceptions at runtime with part of the app that uses jax-ws and jaxb to call a remote xml based webservice.

At runtime as the MDB is picking up messages to process from the queue, I’m getting this exception:

Caused by: java.lang.NullPointerException
at org.jboss.resteasy.resteasy-cdi@3.7.0.Final//org.jboss.resteasy.cdi.CdiInjectorFactory.createConstructor(CdiInjectorFactory.java:91)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.spi.ResteasyProviderFactory.injectedInstance(ResteasyProviderFactory.java:2809)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.core.interception.JaxrsInterceptorRegistry$AbstractInterceptorFactory.createInterceptor(JaxrsInterceptorRegistry.java:170)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.core.interception.JaxrsInterceptorRegistry$OnDemandInterceptorFactory.initialize(JaxrsInterceptorRegistry.java:188)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.core.interception.JaxrsInterceptorRegistry$OnDemandInterceptorFactory.checkInitialize(JaxrsInterceptorRegistry.java:203)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.core.interception.JaxrsInterceptorRegistry$OnDemandInterceptorFactory.getInterceptor(JaxrsInterceptorRegistry.java:214)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.core.interception.JaxrsInterceptorRegistry$AbstractInterceptorFactory.postMatch(JaxrsInterceptorRegistry.java:158)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.core.interception.JaxrsInterceptorRegistry.postMatch(JaxrsInterceptorRegistry.java:421)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.client.jaxrs.internal.ClientConfiguration.getRequestFilters(ClientConfiguration.java:112)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.client.jaxrs.internal.ClientInvocation.getRequestFilters(ClientInvocation.java:408)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.client.jaxrs.internal.ClientInvocation.filterRequest(ClientInvocation.java:582)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.client.jaxrs.internal.ClientInvocation.invoke(ClientInvocation.java:440)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.client.jaxrs.internal.ClientInvocation.invoke(ClientInvocation.java:464)
at org.jboss.resteasy.resteasy-jaxrs@3.7.0.Final//org.jboss.resteasy.client.jaxrs.internal.ClientInvocationBuilder.get(ClientInvocationBuilder.java:189)
at deployment.callsignviz-1.0.war//kh.hamqthclient.HamQTHClient.logon(HamQTHClient.java:70)
at deployment.callsignviz-1.0.war//kh.callsign.spotcollector.service.CallsignProcessorService.(CallsignProcessorService.java:35)

The clue here is the NullPointerException is coming from the HamQTHClient.logon() call, which is my library using jax-ws to call the remote HamQTH service.

Running my JUnits locally, this is definitely a JDK version issue. On Java 8 this code runs fine, but on Java 10 and 11 I get this:

Caused by: java.lang.ClassNotFoundException: javax.xml.bind.PropertyException
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)

… and now I’m remembering the jax-ws removal timeline from JEP-320:

  • Java 9 : deprecated for future removal
  • Java 11: complete removal of javax.xml.bind (jaxb) and javax.xml.ws (jax-ws) (also see here)

I don’t currently have Java 9 installed locally, but I suspect the code would work, but my test local Ubuntu 18.04 has OpenJDK 11, so this is currently my target JRE.

Ok, so what are the migration steps for using jax-ws after Java 8? A quick search found this useful article on migration, and adding explicit dependencies on the jaxb-api and the Glassfish reference implementation was exactly what I needed to get the code to run unmodified on Java 11:




Java 8 will ship without Project Jigsaw, modular dependencies for the Java platform

Around this time two years ago, Oracle gave the Java community two options for the upcoming Java 7 release, Plan A and Plan B, which looked something like this:

Plan A: JDK 7 (as currently defined) Mid 2012
Plan B: JDK 7 (minus Lambda, Jigsaw, and part of Coin) Mid 2011
        JDK 8 (Lambda, Jigsaw, the rest of Coin, ++) Late 2012

Oracle went with Plan B based on community feedback, and we got Java 7 earlier, just with a reduced list of changes.

Now we’re on the verge of seeing the release of Java 8, Oracle has some rather upsetting news that the major changes, namely Project Jigsaw (to introduce modular dependencies into the Java platform), will not be included in Java 8 after all.

I don’t want to see any product released before it’s ready, there’s no point shipping something if its half-baked. But with the Plan A/Plan B approach it seems somehow that we’ve been short-changed. We agreed to delay significant changes to a future release just to keep the new releases coming, and now we’re at the point where we should have received the most significant platform changes that were originally planned for Java 7, to be included in Java 8, and Oracle is telling us ‘sorry, they’re not ready’. ¬†At this point one has to wonder where Oracle’s priorities are with Java, because it’s certainly not looking very promising right now.