--- title: Now is the best time to learn Java | daily.dev description: Java 27 ships with nine JEPs, including compact object headers enabled by default (reducing object header size from 12 to 8 bytes, cutting heap usage up to 20%... canonical: https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Now is the best time to learn Java | daily.dev og:description: Java 27 ships with nine JEPs, including compact object headers enabled by default (reducing object header size from 12 to 8 bytes, cutting heap usage up to 20%... og:url: https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey og:image: https://api.daily.dev/og/posts/kiDsSzpeY.png og:image:alt: Now is the best time to learn Java 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. # Now is the best time to learn Java **[Awesome](https://daily.dev/sources/awesome-coding)** · 8 min read · 7 upvotes · 0 comments ## Summary Java 27 ships with nine JEPs, including compact object headers enabled by default (reducing object header size from 12 to 8 bytes, cutting heap usage up to 20% in some workloads), G1 becoming the default garbage collector everywhere, primitive types in pattern matching (fifth preview), structured concurrency (seventh preview), post-quantum hybrid key exchange for TLS 1.3, PEM encoding API (third preview), lazy constants (third preview), the Vector API's 12th incubator release, and JFR data redaction for sensitive diagnostic data. Kotlin 2.5 beta also adds stable name-based destructuring, experimental companion extensions/blocks, new boolean helper functions, and stable compile-time constants. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What changed with Java 27 and compact object headers? Java 27 enables compact object headers by default, reducing the per-object header on a 64-bit JVM from 96 bits (12 bytes) to 64 bits (8 bytes). This requires no application code changes and can reduce heap usage, improve cache locality, and in applications with huge numbers of small objects, decrease memory consumption by up to 20%. _Developers planning JVM upgrades can track memory and GC changes like this one on daily.dev._ ### Is G1 the default garbage collector in Java 27? Yes, starting with Java 27, G1 is the default garbage collector in every environment, including smaller environments that previously fell back to the serial collector. G1 was already default on server-class machines, but now the JVM always uses it unless a different collector is explicitly chosen, giving more consistent behavior across machines, containers, and production servers. _Teams standardizing GC behavior across environments can follow JVM defaults like this via daily.dev._ ### What preview feature number is structured concurrency at in Java 27? Structured concurrency is in its seventh preview in Java 27. It lets related tasks launched by one request be treated as a single unit of work whose lifetime is tied to the surrounding operation, so failures cancel sibling tasks and observability tools can see that the threads belong together, working especially well alongside virtual threads. _Developers weighing when a concurrency API will stabilize can watch JVM preview progress through daily.dev._ ## Similar posts on daily.dev - [Java 26 Delivers Language Innovation, Library Improvements, Performance and Security](https://daily.dev/posts/java-26-delivers-language-innovation-library-improvements-performance-and-security-26rrhgwjk) · InfoQ · 0 upvotes · 0 comments --- Tags: [#java](https://daily.dev/tags/java), [#quantum-computing](https://daily.dev/tags/quantum-computing), [#kotlin](https://daily.dev/tags/kotlin), [#jvm](https://daily.dev/tags/jvm) [View this post on daily.dev](https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey) ```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":"Now is the best time to learn Java","url":"https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey"},"datePublished":"2026-10-02T12:29:56.607Z","dateModified":"2026-10-02T12:30:14.998Z","description":"Java 27 ships with nine JEPs, including compact object headers enabled by default (reducing object header size from 12 to 8 bytes, cutting heap usage up to 20%...","image":"https://i.ytimg.com/vi/nseYdTzMW64/sddefault.jpg","thumbnailUrl":"https://i.ytimg.com/vi/nseYdTzMW64/sddefault.jpg","isAccessibleForFree":true,"articleSection":"Awesome","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":"Awesome","logo":"https://media.daily.dev/image/upload/s--mj_0cdD8--/f_auto/v1710506099/logos/awesome-coding","url":"https://daily.dev/sources/awesome-coding"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":7},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"java,quantum-computing,kotlin,jvm","timeRequired":"PT8M","video":{"@type":"VideoObject","name":"Now is the best time to learn Java","description":"Java 27 ships with nine JEPs, including compact object headers enabled by default (reducing object header size from 12 to 8 bytes, cutting heap usage up to 20%...","thumbnailUrl":"https://i.ytimg.com/vi/nseYdTzMW64/sddefault.jpg","uploadDate":"2026-10-02T12:29:56.607Z","duration":"PT8M","url":"https://api.daily.dev/r/kiDsSzpeY","embedUrl":"https://www.youtube.com/embed/nseYdTzMW64"}} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Awesome","item":"https://daily.dev/sources/awesome-coding"},{"@type":"ListItem","position":3,"name":"Now is the best time to learn Java"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/now-is-the-best-time-to-learn-java-kidsszpey#faq","mainEntity":[{"@type":"Question","name":"What changed with Java 27 and compact object headers?","acceptedAnswer":{"@type":"Answer","text":"Java 27 enables compact object headers by default, reducing the per-object header on a 64-bit JVM from 96 bits (12 bytes) to 64 bits (8 bytes). 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