How to create an implicit Java class in IDEA?

Question

How to create an implicit Java class in IDEA?

Answer

First, you need a project that uses Java 25 or later, where compact source files are a standard feature. Then, you can create just a file like 'test.java' via the menu <path>File | New | File </path> like this:

void main() {
    println("Hello");
}

This file can be run via the run gutter icon before the method main.

Reference: Supported Java versions and features Simple source files and instance main methods

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