Eclipse JDT Language Server

https://github.com/eclipse/eclipse.jdt.ls

The Eclipse JDT Language Server is a Java language specific implementation of the Language Server Protocol and can be used with any editor that supports the protocol, to offer good support for the Java Language. The server is based on:

• Eclipse LSP4J, the Java binding for the Language Server Protocol,
• Eclipse JDT, which provides Java support (code completion, references, diagnostics…),
• M2Eclipse, which provides Maven support,
• Buildship, which provides Gradle support.

Features

• As you type reporting of parsing and compilation errors
• Code completion
• Javadoc hovers
• Code actions / refactoring
• Code outline
• Code navigation
• Code lens (references/implementations)
• Highlights
• Organize imports
• Type search
• Code formatting (on-type/selection/file)
• Maven pom.xml project support
• Java 9/10/11 support
• Limited Gradle support (Android projects are not supported)
• Annotation processing support (automatic for Maven projects)