Error: Could not find or load main class, but works when .jar is missing from classpath?

Question

I was following this tutorial: https://www.youtube.com/watch?v=UlY_6N98WWs&list=PLIBI8eaaUGfSupVFlMBefGodvWQ9ydq51&index=4 And got this error:

$ java -classpath selenium-server-standalone-3.11.0.jar HelloWorld 
Error: Could not find or load main class HelloWorld

But if I run $ java HelloWorld, it works just fine, and says

Exception in thread "main" java.lang.NoClassDefFoundError: org/openqa/selenium/firefox/FirefoxDriver at 
HelloWorld.main(HelloWorld.java:13) Caused by: 
java.lang.ClassNotFoundException: 
org.openqa.selenium.firefox.FirefoxDriver at 
java.net.URLClassLoader.findClass(URLClassLoader.java:381) at 
java.lang.ClassLoader.loadClass(ClassLoader.java:424) at 
sun.misc.Launcher$AppClassLoader.loadClass(Launcher.j

I’m on Mac terminal, and I tried with CLASSPATHs of . and blank. My $PATH variable is /usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin and seems to be fine.

I tried looking at these pages for the solution: https://docs.oracle.com/javase/tutorial/essential/environment/paths.html https://docs.oracle.com/javase/7/docs/technotes/tools/windows/classpath.html What does "Could not find or load main class" mean?

And it seems like my class path is working fine, but something else is glitchy?

HelloWorld.java

/**
 * Import FirefoxDriver and By from selenium jar
 */
import org.openqa.selenium.By;
import org.openqa.selenium.firefox.FirefoxDriver;

public class HelloWorld{

    public static void main(String args[]) throws Exception{

        // Create a Firefox browser instance
        FirefoxDriver driver = new FirefoxDriver();

        // Navigate to google home page
        driver.get("https://www.google.co.in/");

        // Type hello world in the search field
        driver.findElement(By.name("q")).sendKeys("Hello World");

        // Wait for 10 seconds
        Thread.sleep(10*1000);

        // Close the browser instance
        driver.quit();

    }
}

Selenium Standalone Server version 3.11.0 downloaded from: https://www.seleniumhq.org/download/

I'm running on Mac OS 10.13.3.

Answer 1

Apparently I needed to append the current directory to the class path by appending :. to selenium-server-standalone-3.11.0.jar.

$ java -classpath selenium-server-standalone-3.11.0.jar:. HelloWorld 

Special thanks to lanoxx's comment on https://stackoverflow.com/a/18093929/2423194 that helped me:

I had this problem when I was trying to run a Class with a 3rd party library. I invoked java like this: java -cp ../third-party-library.jar com.my.package.MyClass; this does not work, instead it is necessary to add the local folder to the class path as well (separated by :, like this: java -cp ../third-party-library.jar:. com.my.package.MyClass, then it should work

and also thanks to Sam Orozco for commenting the answer later while I was typing this up.