{"id":129,"date":"2015-11-27T13:19:01","date_gmt":"2015-11-27T12:19:01","guid":{"rendered":"https:\/\/overdespotiet.dk\/blog\/?p=129"},"modified":"2024-06-19T13:34:47","modified_gmt":"2024-06-19T11:34:47","slug":"tracking-down-a-nosuchmethoderror","status":"publish","type":"post","link":"https:\/\/overdespotiet.dk\/blog\/?p=129","title":{"rendered":"Tracking down a NoSuchMethodError"},"content":{"rendered":"
Caused by: java.lang.NoSuchMethodError: org.apache.xml.serializer.Encodings.isRecognizedEncoding(Ljava\/lang\/String;)Z\r\n        at org.apache.xml.serializer.dom3.LSSerializerImpl.write(LSSerializerImpl.java:926)\r\n        at ...<\/pre>\n
If you’ved ever had the unpleasant task of figuring out which of the 200+ JAR dependencies in your project that are causing the a NoSuchMethodError (usually in some XML or webservice code), then this is the trick for you:<\/p>\n
Consider the following POM (distilled\u00a0from a real-world scenario):<\/p>\n
<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n<project xmlns=\"http:\/\/maven.apache.org\/POM\/4.0.0\"\r\n         xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\r\n         xsi:schemaLocation=\"http:\/\/maven.apache.org\/POM\/4.0.0 http:\/\/maven.apache.org\/xsd\/maven-4.0.0.xsd\">\r\n    <modelVersion>4.0.0<\/modelVersion>\r\n\r\n    <groupId>net.bystrup<\/groupId>\r\n    <artifactId>nsm-example<\/artifactId>\r\n    <version>1.0-SNAPSHOT<\/version>\r\n\r\n    <dependencies>\r\n        <dependency>\r\n            <groupId>xalan<\/groupId>\r\n            <artifactId>xalan<\/artifactId>\r\n            <version>2.7.0<\/version>\r\n        <\/dependency>\r\n        <dependency>\r\n            <groupId>xalan<\/groupId>\r\n            <artifactId>serializer<\/artifactId>\r\n            <version>2.7.1<\/version>\r\n        <\/dependency>\r\n    <\/dependencies>\r\n<\/project><\/pre>\n
When parsing an XML document, the error\u00a0at the top of the post might occur… You know the symptom, you know the probable root cause – but how do you find the\u00a0conflicting JARs?<\/p>\n
ClassLoader.getResources()<\/tt><\/b> to the rescue! The following snippet will list all resources\/JARs containing the clas with the missing method:<\/p>\n
import java.net.URL;\r\nimport java.util.Enumeration;\r\n\r\npublic class Main\r\n{\r\n    \/**\r\n     * The project depends on both xalan:2.7.0 and serializer:2.7.1 which both\r\n     * contain the org.apache.xml.serializer.Encodings class, albeit with different\r\n     * signatures...\r\n     *\r\n     * @param argv\r\n     *\/\r\n    public static void main( String argv[] ) throws Exception\r\n    {\r\n        Enumeration<URL> res = new Main().getClass().getClassLoader().getResources( \"org\/apache\/xml\/serializer\/Encodings.class\" );\r\n        while ( res.hasMoreElements() )\r\n        {\r\n            URL url = res.nextElement();\r\n            System.out.println( url.toExternalForm() );\r\n        }\r\n    }\r\n}<\/pre>\n
The operative\u00a0piece of code<\/p>\n
this.getClass().getClassLoader().getResources( \"org\/apache\/xml\/serializer\/Encodings.class\" )<\/pre>\n
might even be evaluated in eg. IDEAs “Evaluate Expression” window (Alt-F8) if\u00a0you’re in a debugging situation.<\/p>\n
The only problem remaining is: How does one remember where to find this guide next time the problem occurs… \ud83d\ude42<\/p>\n","protected":false},"excerpt":{"rendered":"
Caused by: java.lang.NoSuchMethodError: org.apache.xml.serializer.Encodings.isRecognizedEncoding(Ljava\/lang\/String;)Z at org.apache.xml.serializer.dom3.LSSerializerImpl.write(LSSerializerImpl.java:926) at … If you’ved ever had the unpleasant task of figuring out which of the 200+ JAR dependencies in your project that are causing the a NoSuchMethodError (usually in some XML or webservice code), … Continue reading →<\/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":[7,29],"tags":[],"class_list":["post-129","post","type-post","status-publish","format-standard","hentry","category-coding","category-java"],"_links":{"self":[{"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/129","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=129"}],"version-history":[{"count":5,"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/129\/revisions"}],"predecessor-version":[{"id":243,"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/129\/revisions\/243"}],"wp:attachment":[{"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=129"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=129"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/overdespotiet.dk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=129"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}