JDK 26: The new features in Java 26

Java Development Kit (JDK) 26, a planned update to standard Java due in March 2026, now has its first three features slated for it, with the latest being increased application throughput when using the G1 garbage collector (GC).

Proposed September 8, this JEP (JDK Enhancement Proposal), G1 GC: Improve throughput by reducing synchronization, joins two previously slotted features, HTTP/3 for the Client API and Removal of the Java Applet API.

The G1 GC proposal is intended to improve application throughput and latency when using the G1 garbage collector by reducing the amount of synchronization required between application threads and GC threads. Goals include reducing the G1 garbage collector’s synchronization overhead, reducing the size of the injected code for G1’s write barriers, and maintaining the overall architecture of G1, with no changes to user interaction.

The G1 GC proposal notes that although G1, which is the default garbage collector of the HotSpot JVM, is designed to balance latency and throughput, achieving this balance sometimes impacts application performance adversely compared to throughput-oriented garbage collectors such as the Parallel and Serial collectors:

Relative to Parallel, G1 performs more of its work concurrently with the application, reducing the duration of GC pauses and thus improving latency. Unavoidably, this means that application threads must share the CPU with GC threads, and coordinate with them. This synchronization both lowers throughput and increases latency.

A short-term release of Java backed by six months of Premier-level support, JDK 26 will follow the September 16 release of JDK 25, which is a Long-Term Support (LTS) release backed by several years of Premier-level support.

The HTTP/3 proposal calls for allowing Java libraries and applications to interact with HTTP/3 servers with minimal code changes. Goals include updating the HTTP Client API to send and receive HTTP/3 requests and responses; requiring only minor changes to the HTTP Client API and Java application code; and allowing developers to opt in to HTTP/3 as opposed to changing the default protocol version from HTTP/2 to HTTP/3.

HTTP/3 is considered a major version of the HTTP (Hypertext Transfer Protocol) data communications protocol for the web. Version 3 was built on the IETF QUIC (Quick UDP Internet Connections) transport protocol, which emphasizes flow-controlled streams, low-latency connection establishment, network path migration, and security among its capabilities.

Removal of the Java Applet API, now considered obsolete, is also targeted for JDK 26. The Applet API was deprecated for removal in JDK 17 in 2021. The API is obsolete because neither recent JDK releases nor current web browsers support applets, according to the proposal. There is no reason to keep the unused and unusable API, the proposal states.

Other possible features for JDK 26 include features to be previewed in JDK 25, such as structured concurrency; primitive types in patterns, instanceof, and switch; and PEM (Privacy-Enhanced Mail) encodings of cryptographic objects. An experimental feature in JDK 25, JDK Flight Recorder CPU-time profiling, may also be included in JDK 26.