>>107036733
For the simplest test program, you need a public class to contain a public static void method called main that takes an array of strings as its only argument. From there, you can do whatever you like.
Or, you build a test scheme with a framework like JUnit. (See its documentation for how to mark a class as supplying tests.)
Or, you use the new Java 25 way of doing a main class. In that case, you need to use the right runtime or it won't know what to do.
Which one were you trying to do?