I have a library which has root package "scala", and now I have a project using this library, and I have a sub package named "com.zjffdu.scala". And the class file in this package needs to import classes from the library. So I have the following import statement.
import scala._
But because this class is also in package "scala", the scala compiler will look for files in current directory rather than the library.
So how can I explicit to tell scala to import classes from the library.
Thanks
Use this:
import _root_.scala._
As you can see it's not very pretty — the best option is probably to avoid naming one of your packages scala.
And by the way — the root scala package is always preimported (though subpackages, of course, are not).
Related
I'm parsing a XML string to convert it to a JsonNode in Scala using a XmlMapper from the Jackson library. I code on a Databricks notebook, so compilation is done on a cloud cluster. When compiling my code I got this error java.lang.NoSuchMethodError: com.fasterxml.jackson.dataformat.xml.XmlMapper.coercionConfigDefaults()Lcom/fasterxml/jackson/databind/cfg/MutableCoercionConfig; with a hundred lines of "at com.databricks. ..."
I maybe forget to import something but for me this is ok (tell me if I'm wrong) :
import ch.qos.logback.classic._
import com.typesafe.scalalogging._
import com.fasterxml.jackson._
import com.fasterxml.jackson.core._
import com.fasterxml.jackson.databind.{ObjectMapper, JsonNode}
import com.fasterxml.jackson.dataformat.xml._
import com.fasterxml.jackson.module.scala._
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper
import java.io._
import java.time.Instant
import java.util.concurrent.TimeUnit
import javax.xml.parsers._
import okhttp3.{Headers, OkHttpClient, Request, Response, RequestBody, FormBody}
import okhttp3.OkHttpClient.Builder._
import org.apache.spark._
import org.xml.sax._
As I'm using Databricks, there's no SBT file for dependencies. Instead I installed the libs I need directly on the cluster. Here are the ones I'm using :
com.squareup.okhttp:okhttp:2.7.5
com.squareup.okhttp3:okhttp:4.9.0
com.squareup.okhttp3:okhttp:3.14.9
org.scala-lang.modules:scala-swing_3:3.0.0
ch.qos.logback:logback-classic:1.2.6
com.typesafe:scalalogging-slf4j_2.10:1.1.0
cc.spray.json:spray-json_2.9.1:1.0.1
com.fasterxml.jackson.module:jackson-module-scala_3:2.13.0
javax.xml.parsers:jaxp-api:1.4.5
org.xml.sax:2.0.1
The code causing the error is simply (coming from here : https://www.baeldung.com/jackson-convert-xml-json Chapter 5):
val xmlMapper: XmlMapper = new XmlMapper()
val jsonNode: JsonNode = xmlMapper.readTree(responseBody.getBytes())
with responseBody being a String containing a XML document (I previously checked the integrity of the XML). When removing those two lines the code is working fine.
I've read tons of articles or forums but I can't figure out what's causing my issue. Can someone please help me ? Thanks a lot ! :)
Welcome to dependency hell and breaking changes in libraries.
This usually happens, when various lib bring in different version of same lib. In this case it is Jackson.
java.lang.NoSuchMethodError: com.fasterxml.jackson.dataformat.xml.XmlMapper.coercionConfigDefaults()Lcom/fasterxml/jackson/databind/cfg/MutableCoercionConfig; means: One lib probably require Jackson version, which has this method, but on class path is version, which does not yet have this funcion or got removed bcs was deprecated or renamed.
In case like this is good to print dependency tree and check version of Jackson required in libs. And if possible use newer versions of requid libs.
Solution: use libs, which use compatible versions of Jackson lib. No other shortcut possible.
upgrading to 2.12.5 version fixed my issue.
this issue may also appear when there are multiple versions of jackson jars in project lib directory. you should remove the older versions.
I have a lot of successful rest accesses in grails 2.x.x
I simply coded
import grails.plugins.rest.client.*
import grails.util.Holders
import org.codehaus.groovy.grails.web.json.JSONObject
import org.codehaus.groovy.grails.web.json.JSONArray
and Classes JSONObject, JSONArray, RestBuilder, RestResponse where available for further use.
What are the corresponding imports in 4.0.1 and what jars resp. what lines in build.gradle are necessary?
What are the corresponding imports in 4.0.1 and what jars resp. what
lines in build.gradle are necessary?
Grails 4 offers better options than to interact with the classes you asked about but to answer the question as asked...
org.grails.web.json.JSONObject is in grails-web-common-4.0.1.jar. Use import org.grails.web.json.JSONObject.
org.grails.web.json.JSONArray is in grails-web-common-4.0.1.jar. Use import org.grails.web.json.JSONArray.
grails.plugins.rest.client.RestBuilder is in grails-datastore-rest-client-6.1.12.RELEASE.jar. Use import grails.plugins.rest.client.RestBuilder.
grails.plugins.rest.client.RestResponse is in grails-datastore-rest-client-6.1.12.RELEASE.jar. Use import grails.plugins.rest.client.RestResponse.
Depending on what other dependencies you may have in your project those may or may not be pulled in transitively so you may not need to add them to your build.gradle directly. The most likely scenario is you won't need to add anything to pull in grails-web-common-4.0.1.jar but you probably will need to pull in grails-datastore-rest-client-6.1.12.RELEASE.jar which can be done by adding the following to your build.gradle:
compile "org.grails:grails-datastore-rest-client:6.1.12.RELEASE"
If you want to pull in grails-web-common explicitly you could use the following:
compile "org.grails:grails-web-common:4.0.1"
If you are using the BOM correctly, you could simplify that with the following:
compile "org.grails:grails-web-common"
I hope that helps.
In the Swift REPL, how to import (a.k.a. load, evaluate, require) a typical text *.swift file?
I want to use the code from this file: ~/src/Foo.swift
Syntax like this doesn't work: import ~/src/Foo.swift
For comparison:
An equivalent solution in the Swift REPL for a framework is: import Foundation
An equivalent solution in the Ruby REPL for a *.ruby file is: require "~/src/foo"
These are similar questions that are /not/ what I'm asking:
How to use/make a Swift command-line script, executable, module, etc.
How to use/make an XCode playground, project, library, framework, etc.
How to launch the REPL with a pre-existing list of files.
You need to use -I, so if your modulename.swiftmodule file is in ~/mymodules than launch swift with
swift -I ~/mymodules
and then you will be able to import your module
import module name
Should be that easy
In swift,you can't import a typical *.swift file.
For Import Declaration can only be the following syntax:
“
import-declaration → attributesopt import import-kindopt import-path
import-kind → typealias| struct| class| enum| protocol| var| func
import-path → import-path-identifier| import-path-identifier.import-path
import-path-identifier → identifier| operator”
From: Apple Inc. “The Swift Programming Language (Swift 2)”。 iBooks.
which can be described as these formats:
import module
import import kind module.symbol name
import module.submodule
import head.swift is incompatible with import import-kind module.symbol-name
Usually compile the files you want to import as a framework.Then it can be regarded as a module. use -F framework_directory/ to specify 3rd-party frameworks' search path.
Create a file. For example:
// test.swift
import headtest
print("Hello World")
open your terminal
goto the directory where you create the file.
execute command line
swift -F headtest test.swift
And done.
Simply insert the shebang line at the top of your script:
#!/usr/bin/env xcrun swift
You can copy/paste the source code into the repl and execute it.
Not ideal, obviously, but sometimes useful.
Now Swift REPL supports packages. We can do this by the following steps:
In Xcode, select menu File > New > Package. Choose a name for the package, for example MyLibrary.
Copy your codes or .swift files to the Sources/MyLibrary/ directory in your package.
Remember to make your interface public.
In the command line, go to the package directory and run REPL
Like this
cd MyLibrary/
swift run --repl
In the REPL, import your library
Like this
import MyLibrary
Now you can your codes in the REPL.
It looks like it's not possible to import file and get Xcode to use REPL for it using specifications you gave. I think you can still do it creating a proper framework, but it's not exactly what you was looking.
In scala it is common practice to stack package statements to allow shorter imports, but when I load a file using stacked packages into the scala ide and I attempt to use an import starting with the same organization I get a compiler error from what appears to be the presentation compiler. The code compiles fine in sbt outside of the IDE.
An example code snippet is as follows:
package com.coltfred
package util
package time
import com.github.nscala_time.time.Imports._
On the import I get the error object github is not a member of package com.coltfred.util.com.
If I move the import to a single line the error will go away, but we've used this practice frequently in our code base so changing them all to be single line package statements would be a pain.
Why is this happening and is there anything I can do to fix it?
Edit:
I used the eclipse-sbt plugin to generate the eclipse project file for this. The directory structure is what it should be and all of the dependencies are in the classpath.
Edit 2:
It turns out there was a file in the test tree of the util package (which should have been in the same package), but had a duplicate package statement at the top. I didn't check the test tree because it shouldn't affect the compilation of the main tree, but apparently I was wrong.
Not sure why the Scala IDE is not liking this, but you can force the import to start at the top level using _root_:
import _root_.com.github.nscala_time.time.Imports._
See if that avoids irritating the IDE.
This is a common annoyance that annoyed paulp into an attempt to fix it. His idea was that a dir that doesn't contribute class files shouldn't be taken as a package. If you can take util as scala.util, you should do so in preference to foo.util where that util is empty.
The util dir is the usual suspect, because who doesn't have a util dir lying around, and in particular, ./util?
apm#mara:~/tmp/coltfred$ mkdir -p com/coltfred/util/time
apm#mara:~/tmp/coltfred$ mkdir -p com/coltfred/util/com
apm#mara:~/tmp/coltfred$ vi com/coltfred/util/time/test.scala
apm#mara:~/tmp/coltfred$ scalac com/coltfred/util/time/test.scala
./com/coltfred/util/time/test.scala:5: error: object github is not a member of package com.coltfred.util.com
import com.github.nscala_time.time._
^
one error found
apm#mara:~/tmp/coltfred$ cat com/coltfred/util/time/test.scala
package com.coltfred
package util
package time
import com.github.nscala_time.time._
class Test
apm#mara:~/tmp/coltfred$
To debug, find out where the offending package is getting loaded from.
I'm having trouble importing packages into package objects. It didn't seem to work in Eclipse and so I switched to intellij. At one point the feature seemed to be working and so I created package objects for most packages. Now it doesn't seem to be working at all. Here's a package object in file package.scala, the package file itself compiles fine:
package rStrat.rSwing
package testSw //Edited for clarity
object testSw
{
import rStrat._
import rSwing.topUI._
}
and here's a class file from the same module and package.
package rStrat.rSwing.testSw
object MainTest {
def main(args: Array[String])
{
val testApp = new AppWindow //Appwindow is a member of topUI
testApp.open
}
}
It works fine if I import the topUI package straight into the MainTest file. it makes no difference whether I try and import the whole package or a particular class. is this legal scala? Is the problem with the IDEs?
I'm using Scala 2.92 Final, Intellij 11.1.1, JDK 1.6.0_31, Eclipse 3.7.2
Scala does not have first class imports. Where a package can only contain declarations of classes and traits, a package object can contain any other valid Scala declaration like var, val, def, type (type alias), implicit stuff. And although as in any object you can import things, they don't transitively propagate to the rest of the package and are thus not visible to the rest of the world.
This creates the object rStrat.rSwing.testSw.testSw:
package rStrat.rSwing
package testSw //Edited for clarity
object testSw
This creates the package object rStrat.rSwing.testSw.testSw:
package rStrat.rSwing
package testSw //Edited for clarity
package object testSw
This creates the package object rStrat.rSwing.testSw:
package rStrat.rSwing
package object testSw
It's the last one you want.