Is it possible to use sysout without class and main method in Eclipse IDE using Java 9?

You can use the TM Terminal to run JShell in Eclipse:

• If necessary, install TM Terminal (contained only in some Eclipse packages)
• Open a 'Terminal' view in Eclipse: Window > Show View > Other...: Terminal > Terminal
• Launch a new Local Terminal
• Run JShell, e. g. on Windows type "C:\Program Files\Java\jdk-9\bin\jshell" -v followed by Enter

Alternatively, you can use a Scrapbook Page, a built-in feature of the Eclipse Java IDE and which also works with older Java versions. You will have code completion and you can use Java classes of your project:

If this is not a feature ask for Eclipse, a very basic stub that you can come up with is:

public static void main(String[] args) throws Exception {
     jdk.jshell.tool.JavaShellToolBuilder.builder().run();
}

When you execute this, you can further use your debug console as JShell in your IDE.

Sample screenshot: