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Exceptions with deep causes. JRuby only shows the latest level, i.e. 'Exception on level 8' without any insight into the deeper causes.
require 'java'
$CLASSPATH << File.expand_path('..', __FILE__) 8
public class NestedExceptionTest {
public void throwNestedExceptions(int n) {
if (n > 0) {
try {
} catch (Exception e) {
throw new RuntimeException("Exception on level " + n, e);
} else {
throw new RuntimeException("Root cause!");
public static void main(String[] ignored) {
new NestedExceptionTest().throwNestedExceptions(8);

jmiettinen commented Nov 20, 2012

I would expect the JRuby stack trace to contain some information about the root cause but instead it only shows

NativeException: java.lang.RuntimeException: Exception on level 8
  (root) at nested_exceptions.rb:5

without a mention of the root cause.
So, how should I get that information saved, say, when logging? Should I manually inspect NativeException and see what it contains?

I don't think Ruby can throw nested exceptions; I believe JRuby mimics this behavior.

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