How IntelliJ IDEA Enhances Java 11: New Lambda var Support and Migration Tips

IntelliJ IDEA now fully supports the newly released Java 11, offering developers convenient features to adopt the language's updates.

Java 11 Highlights

Among the new language features, JEP 323 introduces the ability to use var for lambda parameter types, allowing shorter and clearer code. For example, a traditional lambda declaration looks like:

BiConsumer<Processor, String> consumer1 = (Processor x, String y) -> x.process(y);

IntelliJ IDEA can automatically remove the explicit parameter types, simplifying the expression.

When annotations are needed on parameters, Java 11 lets developers replace the types with var:

BiConsumer<Processor, String> consumer = (@NotNull Processor x, @Nullable String y) -> x.process(y);

IDEA can transform this to use var without warnings, as shown in the accompanying screenshots.

API Changes in Java 11

Beyond language syntax, Java 11 removes several modules such as Java EE and CORBA. Developers must add explicit dependencies for formerly built‑in APIs like JAXB, which are no longer part of the core runtime.

Java 10 Recap

Java 10 introduced var for local variable type inference. IntelliJ IDEA assists by offering quick‑fix actions to replace explicit types with var, navigation shortcuts (Ctrl/⌘ + Click), and documentation pop‑ups (Ctrl + Q / F1).

Java 9 Overview

Java 9 brought module system (Project Jigsaw) and many convenience factory methods. IntelliJ IDEA provides code inspections that suggest migrations to these new APIs.

Migration Recommendations

To adopt Java 11 smoothly, ensure all project dependencies are up‑to‑date, especially those previously provided by Java EE or CORBA. Updating libraries while minimizing impact on existing code is essential. IntelliJ IDEA simplifies this process with refactoring tools and inspections.

Developers can download the OpenJDK 11 build (or Oracle’s distribution) and start using the new features immediately.