Several errors reported for anonymous Object classes

[fbricon]

Try:

public class Tuples {
    public static void main(String[] args) {
        var tuple = new Object() {
            String name = "Java";
            int age = 25;
        };

        System.out.println(tuple.name +" is "+ tuple.age);
    }
}

You get java.lang.IllegalArgumentException: new java.lang.Object(){} errors on textDocument/codeAction, hover

[Error - 10:02:37 AM] Request textDocument/codeAction failed.
  Message: Internal error.
  Code: -32603 
java.util.concurrent.CompletionException: java.lang.IllegalArgumentException: new java.lang.Object(){}
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:645)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:479)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
Caused by: java.lang.IllegalArgumentException: new java.lang.Object(){}
	at org.eclipse.jdt.core.Signature.createCharArrayTypeSignature(Signature.java:1097)
	at org.eclipse.jdt.core.Signature.createTypeSignature(Signature.java:1293)
	at org.eclipse.jdt.internal.core.SelectionRequestor.acceptLocalVariable(SelectionRequestor.java:488)
	at org.eclipse.jdt.internal.codeassist.SelectionEngine.selectFrom(SelectionEngine.java:1395)
	at org.eclipse.jdt.internal.codeassist.SelectionEngine.select(SelectionEngine.java:1098)
	at org.eclipse.jdt.internal.core.Openable.codeSelect(Openable.java:167)
	at org.eclipse.jdt.internal.core.CompilationUnit.codeSelect(CompilationUnit.java:389)
	at org.eclipse.jdt.internal.core.CompilationUnit.codeSelect(CompilationUnit.java:382)
	at org.eclipse.jdt.ls.core.internal.JDTUtils.findElementsAtSelection(JDTUtils.java:976)
	at org.eclipse.jdt.ls.core.internal.JDTUtils.findElementAtSelection(JDTUtils.java:957)
	at org.eclipse.jdt.ls.core.internal.text.correction.SourceAssistProcessor.getSourceActionCommands(SourceAssistProcessor.java:110)
	at org.eclipse.jdt.ls.core.internal.handlers.CodeActionHandler.getCodeActionCommands(CodeActionHandler.java:208)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$15(JDTLanguageServer.java:649)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:75)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:642)
	... 6 more

[Error - 10:01:53 AM] Oct 19, 2021, 10:01:53 AM Error computing hover
new java.lang.Object(){}
java.lang.IllegalArgumentException: new java.lang.Object(){}
	at org.eclipse.jdt.core.Signature.createCharArrayTypeSignature(Signature.java:1097)
	at org.eclipse.jdt.core.Signature.createTypeSignature(Signature.java:1293)
	at org.eclipse.jdt.internal.core.SelectionRequestor.acceptLocalVariable(SelectionRequestor.java:488)
	at org.eclipse.jdt.internal.codeassist.SelectionEngine.selectFrom(SelectionEngine.java:1395)
	at org.eclipse.jdt.internal.codeassist.SelectionEngine.select(SelectionEngine.java:1098)
	at org.eclipse.jdt.internal.core.Openable.codeSelect(Openable.java:167)
	at org.eclipse.jdt.internal.core.CompilationUnit.codeSelect(CompilationUnit.java:389)
	at org.eclipse.jdt.internal.core.CompilationUnit.codeSelect(CompilationUnit.java:382)
	at org.eclipse.jdt.ls.core.internal.JDTUtils.findElementsAtSelection(JDTUtils.java:976)
	at org.eclipse.jdt.ls.core.internal.HoverInfoProvider.computeHover(HoverInfoProvider.java:97)
	at org.eclipse.jdt.ls.core.internal.handlers.HoverHandler.computeHover(HoverHandler.java:57)
	at org.eclipse.jdt.ls.core.internal.handlers.HoverHandler.hover(HoverHandler.java:43)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$7(JDTLanguageServer.java:562)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:75)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:642)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:479)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

[fbricon]

Eclipse IDE doesn't exhibit this issue

So it's definitely.a jdt.ls bug

[snjeza]

Eclipse IDE doesn't exhibit this issue

I can reproduce the issue in Eclipse too. You should hover over the tuple field.

A simpler case:

public class Test {
    void test() {
        var runnable = new Runnable() {
			public void run() {}
		};
		runnable.run();
    }
}

You get IAE when hovering over runnable.

[snjeza]

A related Eclipse bug - https://bugs.eclipse.org/bugs/show_bug.cgi?id=576778