You can run Java code online without installing any development tools or IDEs on your computer by using various online Java compilers and IDEs. These online platforms allow you to write, compile, and execute Java code directly in your web browser. Here are some popular options:

1. repl.it: repl.it offers an online development environment for various programming languages, including Java. You can write, run, and share Java code in your browser. Visit repl.it – Java to get started.

2. JDoodle: JDoodle provides an online Java compiler and IDE. It allows you to write and run Java code in a web-based editor, and you can choose different Java versions to run your code. Visit JDoodle – Java Online Compiler to use their Java compiler.

3. OnlineGDB: OnlineGDB is an online IDE that supports multiple programming languages, including Java. You can write, compile, and run Java code in a web-based environment. Visit OnlineGDB – Java Online Compiler to start coding in Java.

4. Ideone: Ideone is an online compiler and debugging tool that supports Java. You can write Java code, compile it, and see the output in your browser. Visit Ideone – Java Online Compiler to use their online compiler.

5. CompileJava.net: CompileJava.net is a simple online Java compiler that allows you to write and compile Java code. It provides a straightforward interface for testing Java snippets. Visit CompileJava.net to compile and run Java code online.

6. Coding Ground: Coding Ground by TutorialsPoint offers an online development environment for various programming languages, including Java. You can write, compile, and execute Java code online. Visit Coding Ground – Java to access their Java online IDE.