--- title: Patch Java classes at build time with Quarkus Shim description: Quarkus Shim is a Quarkus extension that lets you patch Java classes from third-party libraries at build time without Java agents or runtime instrumentation.... canonical: https://daily.dev/posts/patch-java-classes-at-build-time-with-quarkus-shim-dlxn5ns4v twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Patch Java classes at build time with Quarkus Shim | daily.dev og:description: Quarkus Shim is a Quarkus extension that lets you patch Java classes from third-party libraries at build time without Java agents or runtime instrumentation.... og:url: https://daily.dev/posts/patch-java-classes-at-build-time-with-quarkus-shim-dlxn5ns4v og:image: https://api.daily.dev/og/posts/Dlxn5NS4V.png og:image:alt: Patch Java classes at build time with Quarkus Shim og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Patch Java classes at build time with Quarkus Shim **[Quarkus](https://daily.dev/sources/quarkus)** · 4 min read · 2 upvotes · 0 comments ## Summary Quarkus Shim is a Quarkus extension that lets you patch Java classes from third-party libraries at build time without Java agents or runtime instrumentation. Using annotations like @Shim, @ShimReplace, @ShimAround, @ShimBefore, and @ShimAfter, you can replace method bodies, wrap existing behavior, or inject code before/after method execution. The transformation uses ASM during Quarkus augmentation, works across JVM, dev, and native modes, and validates signatures at build time. It also supports accessing private fields and methods via ShimFields and ShimMethods helpers, and handles overloaded methods via paramTypes. Limitations include inability to patch JDK classes or abstract/native methods. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Quarkus - a component testing update](https://daily.dev/posts/quarkus---a-component-testing-update-weaukgxrs) · Quarkus · 1 upvotes · 0 comments - [Faster Startup on IBM Semeru with OpenJ9 Shared Classes Cache](https://daily.dev/posts/faster-startup-on-ibm-semeru-with-openj9-shared-classes-cache-nfs5weqbl) · Quarkus · 1 upvotes · 0 comments - [Quarkus: A Runtime and Framework for Cloud-Native Java](https://daily.dev/posts/quarkus-a-runtime-and-framework-for-cloud-native-java-guuchh19i) · Quarkus · 1 upvotes · 0 comments --- Tags: [#java](https://daily.dev/tags/java), [#quarkus](https://daily.dev/tags/quarkus) [View this post on daily.dev](https://daily.dev/posts/patch-java-classes-at-build-time-with-quarkus-shim-dlxn5ns4v) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Patch Java classes at build time with Quarkus Shim","url":"https://daily.dev/posts/patch-java-classes-at-build-time-with-quarkus-shim-dlxn5ns4v","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/patch-java-classes-at-build-time-with-quarkus-shim-dlxn5ns4v"},"datePublished":"2026-07-17T02:21:33.749Z","dateModified":"2026-07-17T02:21:54.938Z","description":"Quarkus Shim is a Quarkus extension that lets you patch Java classes from third-party libraries at build time without Java agents or runtime instrumentation....","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/e7ab97eced21a845aaca4e155a5e5171?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/e7ab97eced21a845aaca4e155a5e5171?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Quarkus","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Quarkus","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/8adf82d719bb4a9492f44a28a27fd396","url":"https://daily.dev/sources/quarkus"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/patch-java-classes-at-build-time-with-quarkus-shim-dlxn5ns4v","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"java,quarkus","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Quarkus","item":"https://daily.dev/sources/quarkus"},{"@type":"ListItem","position":3,"name":"Patch Java classes at build time with Quarkus Shim"}]} ```