What is the Scala classpath?

I've been trying to use a jar called PasswordHash.jar in my project. I am using sbt, so I put the jar in lib/. Now it is in the classpath, but I don't know what that means.

I've tried:

• import PasswordHash
• import PasswordHash.jar
• import com.PasswordHash
• import com.PasswordHash.jar
• import org.PasswordHash
• import org.PasswordHash.jar
• import java.PasswordHash
• import java.PasswordHash.jar
• import jar.PasswordHash

The jar was built from a Java file which didn't have a package statement.

EDIT:

Scala file:

~/FileShare/shared/src/main/scala/com/michael/fileshare/shared/Collatz.scala

package com.michael.fileshare.shared
import  com.michael.fileshare.shared.PasswordHash

Java file:

~/FileShare/shared/src/main/java/com/michael/fileshare/shared/PasswordHash.java

package com.michael.fileshare.shared

Error message:
object PasswordHash is not a member of package com.michael.fileshare.shared

The Scala file unsuccessfully tries to import the Java file, but a different Scala file successfully imports this Scala file.

If it helps, I'm on Ubuntu focal.

import foo.bar.x; means something very very simple:

"In this source file, any time any mention of a type is just x, assume it reads foo.bar.x", and that is all it means. It doesn't mean that a file is loaded from disk when the import statement is 'run' (in fact, an import statement isn't "run" at all), and it is a literal no-op if you never mention x.

In scala it's mostly the same, though stuff like implicits are processed IIRC.

All your import x.jar statements are definitely wrong, import is not how you do that, at all. You just name type shortcuts, that's all that does. The job of locating the class file with the representation of that type is not part of your source file - it's part of the build, i.e., the arguments passed to javac or scalac.

Okay, what's the solution?

you've made multiple errors here. The first one is that package-less classes cannot be imported at all. You MUST have a package declaration.

The second is that the class file must then be in the classpath as you compile your scala file. The rule for class path is as follows: Each entry in a classpath is either a directory or a jar file. Then, packages follow directories.

So, if you have:

import com.foo.PassHash;

public class Example {
    PassHash hash = new PassHash();
}

and your classpath is, say: javac -cp whatever/x.jar Example.java, then whatever/x.jar must exist, must be a jar file (or directory), and within that jar file or directory, there needs to be a directory named com, containing a directory named foo, containing a file named PassHash.class. Once you have that, the above will compile fine, and it's analogous in scala.