Java IDE

Eclipse

Eclipse is an open-source development platform that can function as a Java IDE.

NetBeans

NetBeans Integrated Development Environment (IDE) 4.0 is the first open source IDE to support the new J2SE 5.0 "Tiger" language features, and is the first IDE to base its project system entirely on Apache Ant.

DrJava

DrJava is a lightweight development environment for writing Java programs. It is designed primarily for students, providing an intuitive interface and the ability to interactively evaluate Java code. It also includes powerful features for more advanced users. DrJava is available for free under the DrJava Open Source License, and it is under active development by the JavaPLT group at Rice University.

BlueJ

BlueJ is a Java IDE and teaching environment.

JCreator Lite (LE edition)

Java IDE for use with Sun's JDK. Provides an editor with syntax highlighting, project management, project templates, and customizable user interface. I haven't tried the new LE version yet, but you'll have to provide an a valid email address to get the download details.

Jipe

A free ide written in Java with syntax highlighting and project management. It does not appear to have been updated in a long time however.

J-Editor

A Free Java editor package written in Java.

Free Java v1.0

Free Java is an integrated development environment designed to help beginners write Java programs. It includes syntax highlighting and requires JDK 1.3 or higher.

JJct

JJct is a Java IDE written for Windows 95/NT. It started out as a simple editor and evolved into a multi-threaded Java development environment.