Scala import not working - object is not a

问题:

I have an issue when trying to import in scala. The object Database exists under com.me.project.database but when I try to import it:

import com.me.project.database.Database

I get the error:

object Database is not a member of package com.me.project.controllers.com.me.project.database

Any ideas what the problem is?

Edit:

It is worth mentioning that the import is in the file Application.scala under the package com.me.project.controllers, I can't figure out why it would append the import to the current package though, weird...

Edit 2:

So using:

import _root_.com.me.project.database.Database

Does work as mentioned below. But should it work without the _root_? The comments so far seem to indicate that it should.

Answer:

So it turns out that I just needed to clean the project for the import to work properly, using both:

import _root_.com.me.project.database.Database

import com.me.project.database.Database

are valid solutions. Eclipse had just gotten confused.

回答1:

imports can be relative. Is that the only import you have? be careful with other imports like

import com.me

ultimately, this should fix it, then you can try to find more about it:

import _root_.com.me.project.database.Database

回答2:

In my case I also needed to check that object which is not found as a member of package is compiled successfully.

回答3:

In my case I had to run sbt clean.

回答4:

I realize this question already has an accepted answer, but since I experienced the same problem but with a different cause I figured I'd add an answer.

I had a bunch of interdependent projects which suddenly needed a root import in order to compile. It turned out that I had duplicated the package declaration in a single file. This caused some kind of chain reaction and made it very hard to find the source of the problem.

In summary I had

package foo.bar
package foo.bar

on the top of the file instead of just

package foo.bar

Hope this saves someone some really tedious error hunting.

回答5:

Java -> Scala conversion without cleaning

Don't forget to clean if you convert some file in a project from Java to Scala. I had a continuous integration build running where I couldn't get things to work, even though the build was working locally, after I had converted a Java class into a Scala object. Solution: add 'clean' to the build procedure on the CI server. The name of the generated .class file in Scala is slightly different than for a Java class, I believe, so this is very likely what was causing the issue.

回答6:

If you are using gradle as your build tool, then ensure that jar task is not disabled.

I had multiple modules in my project, where one module was dependent on a few other modules. However, I had disabled jar task in build.gradle:

jar { enabled = false }

That caused it to fail to resolve classes in the dependent modules and fail with the above error.

回答7:

I will share my story, just in case it may help someone.

Scenario: intellij compilation succeeds, but gradle build fails on import com.foo.Bar, where Bar is a scala class.

TLDR reason: Bar was located under src/main/java/... as opposed to src/main/scala/...

Actual reason: Bar was not being compiled by compileScala gradle task (from gradle scala plugin) because it looks for scala sources only under src/<sourceSet>/scala.

From docs.gradle.org:

All the Scala source directories can contain Scala and Java code. The Java source directories may only contain Java source code.

Hope this helps

回答8:

I had a similar situation, which was failing in both IntelliJ and maven on the command line. I went to apply the suggested temp fix (adding _root_) but intellij was glitching so bad that wasn't even possible.

Eventually I noticed that I had mis-created a package so that it repeated the whole path of the package. That meant that the directory my class was in had a subfolder called "com", and the start of my file looked like:

package com.mycompany.mydept.myproject.myfunctionality.sub1

import com.holdenkarau.spark.testing.DataFrameSuiteBase 

where I had another package called com.mycompany.mydept.myproject.myfunctionality.sub1.com.mycompany.mydept.myproject.myfunctionality.sub2

And the compiler was looking for "holdenkarau" under com.mycompany.mydept.myproject.myfunctionality.com and failing.

回答9:

I had a similar problem but none of the solutions here worked for me. What did work however was a simple restart of my machine.

Perhaps it was something with my Intellij but after a quick restart, everything seems to be working fine.

回答10:

I had this issue while using Intellij and the built-in sbt shell (precisely, I was trying to run the command console, which invokes a compiler check of the code).

In my case, after trying the other suggested solutions on this thread, I found that I could restart the sbt shell and it would go away. There's a button on the left-hand side of a looped green arrow and a small grey square which does this in one click (obviously, this is subject to Jet Brains not changing the design of the IDE!!!).

I hope this helps some people get past this issue quickly.