New to Java, need some help

[DrAgonmoray]

Hio. I'm new to Java, and OOP. I am using NetBeans IDE.

I've been googling around, but I can't seem to find a specific answer to what I am looking for. What exactly IS a package, and a library?

Also, I've been looking at some tutorials and things, and I want to know what is mandatory and what is just popular trend. Do all .java files need a main class, and do all projects need a Main.java file?

Any help would be appreciated. :)

[Navatha]

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[DrAgonmoray]

So everything needs a class, and inside that class a function called main? I was testing some things.

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, world!");
    }
}

That worked, but it didn't work when I removed the public class main (and it's curly brace) and it did not work when I changed the name of the main function. Is this correct?

[Norm]

The main() method your talking about is a requirement from the Java program as THE method it will call when starting the execution of your program. Any class you start execution of with the java command must have that method.

There does NOT have to be a class named Main. The java program doesn't look for or require a class with that name. That name is a convention used by IDEs

[Eranga]

That worked, but it didn't work when I removed the public class main (and it's curly brace) and it did not work when I changed the name of the main function. Is this correct?

Did you test the code without that line? If so what happen, any error message?

[al_Marshy_1981]

So everything needs a class, and inside that class a function called main? I was testing some things.

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, world!");
    }
}

That worked, but it didn't work when I removed the public class main (and it's curly brace) and it did not work when I changed the name of the main function. Is this correct?

Every "library" needs an access point that is a main(). It needs to be static because static requires no instance declaration of the class, it needs to be public so it is accessible to all programs it needs curly braces because everything inside them defines a function.