javazoom package works in main but fails in subroutine (.NoClassDefFoundError: javazoom/jl/decoder/JavaLayerException)

Question

I am building an MP3 player in java and the script I have written can play an mp3 in main but when I put the same code in a subroutine in a different java file, it fails.

Here is the script when its in the main (StandAlone.java):

import javazoom.jl.decoder.Bitstream;
import javazoom.jl.decoder.JavaLayerException;
import javazoom.jl.player.advanced.AdvancedPlayer;

import java.io.FileInputStream;
import java.io.IOException;

public class Stand_Alone {
    public static void main(String[] args) {
        String mp3FilePath = "song.mp3";

        try (FileInputStream fileInputStream = new FileInputStream(mp3FilePath)) {
            AdvancedPlayer player = new AdvancedPlayer(fileInputStream);

            player.play();

        } catch (JavaLayerException | IOException e) {
            e.printStackTrace();
        }
    }
}

Here is the code as a main and subroutine (Main.java and SongPlayer.java):

public class Main {

    public static void main(String[] args) {
SongPlayer.load();
    }
}

import javazoom.jl.decoder.Bitstream;
import javazoom.jl.decoder.JavaLayerException;
import javazoom.jl.player.advanced.AdvancedPlayer;

import java.io.FileInputStream;
import java.io.IOException;

public class SongPlayer {
    public static void load()  {
       String mp3FilePath = "song.mp3";
       System.out.println(mp3FilePath);
       try (FileInputStream fileInputStream = new FileInputStream(mp3FilePath)) {
           AdvancedPlayer player = new AdvancedPlayer(fileInputStream);

            player.play();

        } catch (JavaLayerException | IOException e) {
            e.printStackTrace();
      }
    }
}

I am using Windows, I run it in the command prompt with the commands:

javac -cp javazoom_1.0.1.jar SongPlayer.java Main.java
java Main

The two scripts, the song and the javazoom jar are all in the same folder.

The result of running the command is:

Exception in thread "main" java.lang.NoClassDefFoundError: javazoom/jl/decoder/JavaLayerException
        at Main.main(Main.java:4)
Caused by: java.lang.ClassNotFoundException: javazoom.jl.decoder.JavaLayerException
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
        ... 1 more

The question is, why is java not able to see javazoom package when commands are launched from a subroutine, when it is able to see it from main in the stand alone case.

How can I get java to see javazoom from the subroutine?

Please help me, this is driving me nuts and halting my progress. I could put everything in one big java file but that's messy and confusing.