If you catch and rethrow exceptions in Java, you probably know about exception chaining already: You simply give the exception you “wrap” as second argument to your Exception like this<\/p>\n
try { … }
\n catch (Exception e) {
\n throw new CustomException(“something went wrong”, e);
\n }<\/p>\n
and if you look at the stack trace of the newly thrown exception, the original one is listed as “Caused by:”. Now today I had the rather “usual” use case of cleanup up a failing action and the cleanup itself was able to throw as well. So I had two causing exceptions and I wanted to conserve both of them, including their complete cause chain, in a new exception. Consider the following example:<\/p>\n
try { … }
\n catch (Exception e1) {
\n try { … }
\n catch (Exception e2) {
\n \/\/ how to transport e1 and e2 in a new exception here?!
\n }
\n throw e1;
\n }<\/p>\n
My idea here was to somehow tack the exception chain of `e1` onto the exception chain of `e2`, but Java offered no solution for this. So I hunted for my own one:<\/p>\n
public static class ChainedException extends Exception {
\n public ChainedException(String msg, Throwable cause) {
\n super(msg, cause);
\n }
\n public void appendRootCause(Throwable cause) {
\n Throwable parent = this;
\n while (parent.getCause() != null) {
\n parent = parent.getCause();
\n }
\n parent.initCause(cause);
\n }
\n }<\/p>\n
Now I only had to base the exceptions I actually want to chain on `ChainedException` and was able to do this (in fact I based all of them on this class):<\/p>\n
try { … }
\n catch (ChainedException e1) {
\n try { … }
\n catch (ChainedException e2) {
\n e2.appendRootCause(e1);
\n throw new ChainedException(“cleanup failed”, e2);
\n }
\n throw e1;
\n }<\/p>\n
Try it out yourself – you’ll see the trace of `e1` at the bottom of the cause chain of `e2`. Quite nice, eh?<\/p>\n","protected":false},"excerpt":{"rendered":"
If you catch and rethrow exceptions in Java, you probably know about exception chaining already: You simply give the exception you “wrap” as second argument to your Exception like this try { … } catch (Exception e) { throw new CustomException(“something went wrong”, e); } and if you look at the stack trace of the … Continue reading Exception chaining in Java<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,25],"tags":[],"class_list":["post-1078","post","type-post","status-publish","format-standard","hentry","category-coding","category-tips"],"_links":{"self":[{"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/posts\/1078","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/comments?post=1078"}],"version-history":[{"count":4,"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/posts\/1078\/revisions"}],"predecessor-version":[{"id":1082,"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/posts\/1078\/revisions\/1082"}],"wp:attachment":[{"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/media?parent=1078"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/categories?post=1078"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.thomaskeller.biz\/blog\/wp-json\/wp\/v2\/tags?post=1078"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}