Now that Java 18 is features complete (Rampdown Phase One at the day of writing), it\u2019s time to walk throught all the functionalities that brings to us, developers, this new version.<\/p>\n
This article is part of a series on what\u2019s new on the last versions of Java<\/a>, for those who wants to read the others, here are the links : Java 17<\/a>, Java 16<\/a>, Java 15<\/a>, Java 14<\/a>, Java 13<\/a>, Java 12<\/a>, Java 11<\/a>,\u00a0Java 10,<\/a>\u00a0and\u00a0Java 9<\/a>.<\/p>\n With the JEP 400, the default charset becomes UTF-8 for all OS and in all locales.\nIt is possible to use the More information in the JEP-400<\/a>.<\/p>\n Addition of a new JavaDoc @snippet<\/code>code>@snippet<\/code<\/a> tag which can be used to define a code snippet. This is more flexible than the existing @code<\/code>code>@code<\/code<\/a> tag, does not need to escape special characters, and even allows you to include snippets of code from an external file.<\/p>\n Example of a fragment defined within the JavaDoc:<\/p>\n Example of a fragment defined outside the JavaDoc:<\/p>\n This fragment points to the example<\/strong> section of the There are several possible options for formatting and including external fragments; your fragments then become executable, you can even define them in JUnit tests for example, so that they are tested with the rest of your code.\nMore example in this article by Gunnar Morling: Executable JavaDoc Code Snippets <\/a>.<\/p>\n More information in the JEP-413<\/a>.<\/p>\n This JEP adds to the OpenJDK distribution a minimalist web server that allows you to serve static files from a directory via a command line tool: By default, this web server binds to localhost (configurable via In addition to a command line tool, you can use the More examples of the Java API usage in the article Working with the Simple Web Server<\/a> by Julia Boes.<\/p>\n More information in the JEP-408<\/a>.<\/p>\n Finalization is a mechanism by which it is possible to automatically perform actions just before the destruction of an object. This mechanism has a set of problems, among others, it delays the moment when these actions are performed to a garbage collection and a badly coded Since java 9 and the deprecation of the JEP 421 takes the removal of finalization a step further by depreciating for removal the finalization mechanism itself. You can now test your code without finalization via the JVM option More information in the JEP-421<\/a>.<\/p>\n Each new version of the JDK brings its performance optimizations (including GC and intrisics methods), and security improvements. This one also, and we can note, among other things, optimizations in G1 GC (improvement of the management of remembered sets, see JDK-8017163<\/a>) and Parallel GC, as well as in the management of encoding of strings.\nAnother notable addition is support for String de-duplication<\/a> for the garbage collectors Serial GC, Parallel GC and ZGC.<\/p>\n We can also note two important JEPs on internal mechanisms of the JVM:<\/p>\n Other changes in terms of security have been implemented, you can read this article by Sean Mullan on the subject: JDK 18 Security Enhancements<\/a>.<\/p>\n The following features remain in preview (or in incubator module).<\/p>\n For details on these, you can refer to my previous articles.<\/p>\n Various JDK additions:<\/p>\nJEP 400: UTF-8 by Default<\/h2>\n
file.encoding<\/code> system property to configure a different default charset or to configure it to COMPAT<\/code> to revert to the previous mode.<\/p>\nJEP 413: Code Snippets in Java API Documentation<\/h2>\n
\n\/**\n * The following code shows how to use {@code Optional.isPresent}:\n * {@snippet :\n * if (v.isPresent()) {\n * System.out.println(\"v: \" + v.get());\n * }\n * }\n *\/\n<\/pre>\n\n\/**\n * The following code shows how to use {@code Optional.isPresent}:\n * {@snippet file=\"ShowOptional.java\" region=\"example\"}\n *\/\n<\/pre>\nShowOptional.java<\/code> file:<\/p>\n\npublic class ShowOptional {\n void show(Optional v) {\n \/\/ @start region=\"example\"\n if (v.isPresent()) {\n System.out.println(\"v: \" + v.get());\n }\n \/\/ @end\n }\n}\n<\/pre>\nJEP 408: Simple Web Server<\/h2>\n
jwebserver<\/code>.<\/p>\n-b<\/code>), uses port 80 (configurable via -p<\/code>), and serves static files in the current directory (configurable via -d<\/code>).\nEach access will be logged in the standard output.<\/p>\nSimpleFileServer<\/code> class to instantiate a web server through its Java API.<\/p>\n\nvar server = SimpleFileServer.createFileServer(new InetSocketAddress(8080), \n Path.of(\"\/some\/path\"), OutputLevel.VERBOSE);\nserver.start()\n<\/pre>\n
JEP 421: Deprecate Finalization for Removal<\/h2>\n
finalize()<\/code> method can resurect the reference to be destroyed.<\/p>\nfinalize()<\/code> method of the Object <\/code> class, it is not recommended to use it anymore and, to free resources linked to a class, it is advisable to use other mechanisms such as the try-with-resource<\/code> or the new Cleaner<\/code> api.<\/p>\n--finalization=disabled<\/code>.<\/p>\nInternal changes, performance, and security<\/h2>\n
Features that remain in preview<\/h2>\n
Miscellaneous<\/h2>\n
Duration.isPositive()<\/code><\/li>\n\nMath<\/code> and StrictMath<\/code> saw the addition of many new methods : ceilDiv<\/code>, ceilDivExact<\/code>, ceilMod<\/code>, divideExact<\/code>, floorDivExact<\/code> and unsignedMultiplyHigh<\/code><\/li>\n<\/ul>\n