BlueJ - BlueJ is an Integrated Development Environment for Java, developed mainly for educational purposes...
AWS Cloud9 - AWS Cloud9 is a cloud-based integrated development environment (IDE) that lets you write, run, and debug your code with just a browser.
IntelliJ IDEA - Capable and Ergonomic IDE for JVM
replit - Code, create, andlearn together. Use our free, collaborative, in-browser IDE to code in 50+ languages — without spending a second on setup.
Netbeans - NetBeans IDE 7.0. Develop desktop, mobile and web applications with Java, PHP, C/C++ and more. Runs on Windows, Linux, Mac OS X and Solaris. NetBeans IDE is open-source and free.
Koding - A new way for developers to work.