How to install Javascript Engine in GraalVM

I've already mentioned it in the reference below, but just for easy reference for me.

The JavaScript engine no longer comes installed by default in the GraalVM. You have to install it as follows:

% ./gu install js
Downloading: Artifacts catalog from gds.oracle.com
Skipping ULN EE channels, no username provided.
Downloading: Component catalog from www.graalvm.org
Processing Component: Graal.js
Processing Component: ICU4J
Processing Component: TRegex
Additional Components are required:
    ICU4J (org.graalvm.icu4j, version 23.0.0), required by: Graal.js (org.graalvm.js)
    TRegex (org.graalvm.regex, version 23.0.0), required by: Graal.js (org.graalvm.js)
Downloading: Component js: Graal.js from gds.oracle.com
Downloading: Component org.graalvm.icu4j: ICU4J from gds.oracle.com
Downloading: Component org.graalvm.regex: TRegex from gds.oracle.com
Installing new component: TRegex (org.graalvm.regex, version 23.0.0)
Installing new component: ICU4J (org.graalvm.icu4j, version 23.0.0)
Installing new component: Graal.js (org.graalvm.js, version 23.0.0)

References

Upgrading to Jakarta 10

https://randomthoughtsonjavaprogramming.blogspot.com/2022/12/upgrading-to-jakarta-10.html

NullPointerException in Stream

Just a small blurb. I recently helped a colleague who got a NullPointerException whilst dealing with streams.

It looked very innocuous at first.

  @Test(expectedExceptions = NullPointerException.class)
  public void testStream() {
    Optional<String> first = Stream.of(new Person(null, "mrBear"), new Person("George", "Boole"),
            new Person("Ada", "Lovelace"),
            new Person("Tim", "Berners-Lee"), new Person("James", "Gosling"), new Person("Linus", "Torvalds"))
        .map(Person::firstName).findFirst();
  }

Well, it turns out that, if you have a list with null-values, and you try a findFirst() on the stream, and the first value is null, Java will attempt to wrap the null-value into an Optional, which is not allowed.

You get a fancy stacktrace, that shows just this:

java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:208)
	at java.base/java.util.Optional.of(Optional.java:113)
	at java.base/java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:194)
	at java.base/java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:191)
	at java.base/java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:150)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:647)
	at com.mrbear.streams.NullPointerExceptionTest.testStream(NullPointerExceptionTest.java:18)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
	at org.testng.internal.Invoker.invokeMethod(Invoker.java:571)
	at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:707)
	at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:979)
	at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
	at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
	at org.testng.TestRunner.privateRun(TestRunner.java:648)
	at org.testng.TestRunner.run(TestRunner.java:505)
	at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
	at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
	at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
	at org.testng.SuiteRunner.run(SuiteRunner.java:364)
	at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
	at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
	at org.testng.TestNG.runSuitesSequentially(TestNG.java:1187)
	at org.testng.TestNG.runSuitesLocally(TestNG.java:1116)
	at org.testng.TestNG.runSuites(TestNG.java:1028)
	at org.testng.TestNG.run(TestNG.java:996)
	at com.intellij.rt.testng.IDEARemoteTestNG.run(IDEARemoteTestNG.java:66)
	at com.intellij.rt.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:105)

Just something to keep in mind.