How to run multiple java class files from command prompt?

Question

I have multiple java files in a single directory that are related to a single program (Main). I have been using the following in the command prompt,

javac -cp . game/textbased/*.java

java -cp . game/textbased/Main

All related files are in a package called game.textbased. The parent folder series is textbasedgame/src/game/textbased.

I am not sure what is going wrong, the java files seem to compile as nessessary, however, when I try to run I get the following:

Exception in thread "main" java.io.FileNotFoundException: items.dat (The system cannot find the file specified)
        at java.base/java.io.FileInputStream.open0(Native Method)
        at java.base/java.io.FileInputStream.open(FileInputStream.java:216)
        at java.base/java.io.FileInputStream.<init>(FileInputStream.java:157)
        at java.base/java.io.FileInputStream.<init>(FileInputStream.java:111)
        at java.base/java.io.FileReader.<init>(FileReader.java:60)
        at game.textbased.WonderLand.loadItems(WonderLand.java:310)
        at game.textbased.WonderLand.initGame(WonderLand.java:63)
        at game.textbased.WonderLand.<init>(WonderLand.java:24)
        at game.textbased.Main.main(Main.java:6)

I am really not sure what is going wrong, and how to run the files from here. I have read other stack overflow inqueries of a similar nature, and generally they say to go from a higher directory but that has not been working for me. I tried going from outside src, or from within the textbased folder, but only going from within the src folder has given me this particular error.

Thanks!