How to open a Java class file?

In Windows systems, you can use Java development tools such as Eclipse or IntelliJ IDEA to open Java class files. Follow these steps:

1. Open a development tool for Java (such as Eclipse, IntelliJ IDEA, etc).
2. Create a new Java project or open an existing Java project.
3. Copy the class files to the source code folder of the project. The source code folder is usually named “src” or “src/main/java”.
4. Refresh or rebuild the project in the development tool to ensure that the class files are properly loaded into the project.
5. Locate the corresponding class file in the project’s package structure and double-click to open it.

If you just want to view the contents of a class file, you can also use Java decompilation tools (such as JD-GUI, Jad, etc.) to open the class file, which can convert the class file into readable Java source code.

One option would be:
“In Mac or Linux systems, you can use command line tools such as vim, emacs, or text editors like Sublime Text, Atom, etc., to open and view class files.”