Styjun

What is a Centaur Thief's climbing speed?

Have 1.5% of all nuclear reactors ever built melted down?

Using credit/debit card details vs swiping a card in a payment (credit card) terminal

Need to understand my home electrical meter to see why bill is so high and/or if neighbor is on same meter

High resistance, no current. What's the point of a potential then?

Any advice on creating fictional locations in real places when writing historical fiction?

How strong are Wi-Fi signals?

My employer faked my resume to acquire projects

Sitecore 9.0 works with solr 7.2.1?

What to keep in mind when telling an aunt how wrong her actions are, without creating further family conflict?

Python program to take in two strings and print the larger string

Why does Mjolnir fall down in Age of Ultron but not in Endgame?

A Riley Respite

Teacher help me explain this to my students

Can I tell a prospective employee that everyone in the team is leaving?

Count Even Digits In Number

Compaq Portable vs IBM 5155 Portable PC

Website returning plaintext password

Is it rude to call a professor by their last name with no prefix in a non-academic setting?

I unknowingly submitted plagarised work

NIntegrate doesn't evaluate

How to Pin Point Large File eating space in Fedora 18

Python program to find the most frequent letter in a text

How did these characters "suit up" so quickly?

How to call java method taking parameter as List> from Scala

How do I use reflection to call a generic method?How do I call one constructor from another in Java?How do I create a Java string from the contents of a file?How do I address unchecked cast warnings?How to get an enum value from a string value in Java?Efficiency of Java “Double Brace Initialization”?Where does Scala look for implicits?How to convert a java.util.List to a Scala listTranslating generic wildcards from Java to ScalaPlay! failing to convert java list to scala list

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty height:90px;width:728px;box-sizing:border-box;

4

I am trying to call a java method which takes List<Class<?>> from scala.

The compilation fails with

type mismatch;
 found : java.util.List[Class[T]] where type T <: Person.type
 required: java.util.List[Class[_]]

I tried using JavaConverters but get the same error.

Java method:

void registerClasses(List<Class<?>> var1);

Calling from Scala:

def registerEntities() = registry.registerClasses(List(Person.getClass).asJava)

java scala generics

share|improve this question

edited Mar 24 at 7:55

pme

4,11511935

asked Mar 24 at 3:50

soopersooper

233

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Not a solution, but what happens when you change the Java side to use a raw type, so just List var1)?
  
  – GhostCat
  Mar 24 at 4:59
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @GhostCat - Java side is a third party library. So, can't really change it.
  
  – sooper
  Mar 24 at 5:12
  
  

  
  
  
  

add a comment | 

4

I am trying to call a java method which takes List<Class<?>> from scala.

The compilation fails with

type mismatch;
 found : java.util.List[Class[T]] where type T <: Person.type
 required: java.util.List[Class[_]]

I tried using JavaConverters but get the same error.

Java method:

void registerClasses(List<Class<?>> var1);

Calling from Scala:

def registerEntities() = registry.registerClasses(List(Person.getClass).asJava)

java scala generics

share|improve this question

edited Mar 24 at 7:55

pme

4,11511935

asked Mar 24 at 3:50

soopersooper

233

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Not a solution, but what happens when you change the Java side to use a raw type, so just List var1)?
  
  – GhostCat
  Mar 24 at 4:59
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @GhostCat - Java side is a third party library. So, can't really change it.
  
  – sooper
  Mar 24 at 5:12
  
  

  
  
  
  

add a comment | 

I am trying to call a java method which takes List<Class<?>> from scala.

The compilation fails with

type mismatch;
 found : java.util.List[Class[T]] where type T <: Person.type
 required: java.util.List[Class[_]]

I tried using JavaConverters but get the same error.

Java method:

void registerClasses(List<Class<?>> var1);

Calling from Scala:

def registerEntities() = registry.registerClasses(List(Person.getClass).asJava)

java scala generics

share|improve this question

edited Mar 24 at 7:55

pme

4,11511935

asked Mar 24 at 3:50

soopersooper

233

type mismatch;
 found : java.util.List[Class[T]] where type T <: Person.type
 required: java.util.List[Class[_]]

void registerClasses(List<Class<?>> var1);

def registerEntities() = registry.registerClasses(List(Person.getClass).asJava)

share|improve this question

edited Mar 24 at 7:55

pme

4,11511935

asked Mar 24 at 3:50

soopersooper

233

share|improve this question

edited Mar 24 at 7:55

pme

4,11511935

asked Mar 24 at 3:50

soopersooper

233

edited Mar 24 at 7:55

pme

4,11511935

edited Mar 24 at 7:55

pme

4,11511935

asked Mar 24 at 3:50

soopersooper

233

asked Mar 24 at 3:50

soopersooper

233

1 Answer
1

active

oldest

votes

3

The problem is that the inferred type for Person.getClass is not the one you want. You need to specify the expected type, and this can be done by an explicit type parameter

registry.registerClasses(List[Class[_]](Person.getClass).asJava)

(I don't understand why type ascription doesn't work here:

registerClasses(List(Person.getClass: Class[_]).asJava)

type mismatch;
 found : java.util.List[Class[_$2]] where type _$2
 required: java.util.List[Class[_]]
Note: Class[_$2] <: Class[_], but Java-defined trait List is invariant in type E.
You may wish to investigate a wildcard type such as `_ <: Class[_]`. (SLS 3.2.10)

So far as I can tell it should.)

share|improve this answer

edited Mar 24 at 7:15

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  I can't get the type ascription to work, but it seems the type parameter works, so +1.
  
  – Brian McCutchon
  Mar 24 at 6:43
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @BrianMcCutchon That's really surprising, thanks.
  
  – Alexey Romanov
  Mar 24 at 7:16
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Alexey Romanov - Thanks. Type parameter works. However, it puzzles me why implicit conversion doesn't. IntelliJ doesn't complain but maven compilation fails.
  
  – sooper
  Mar 25 at 0:57
  

  
  
  
  

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f55320574%2fhow-to-call-java-method-taking-parameter-as-listclass-from-scala%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

3

The problem is that the inferred type for Person.getClass is not the one you want. You need to specify the expected type, and this can be done by an explicit type parameter

registry.registerClasses(List[Class[_]](Person.getClass).asJava)

(I don't understand why type ascription doesn't work here:

registerClasses(List(Person.getClass: Class[_]).asJava)

type mismatch;
 found : java.util.List[Class[_$2]] where type _$2
 required: java.util.List[Class[_]]
Note: Class[_$2] <: Class[_], but Java-defined trait List is invariant in type E.
You may wish to investigate a wildcard type such as `_ <: Class[_]`. (SLS 3.2.10)

So far as I can tell it should.)

share|improve this answer

edited Mar 24 at 7:15

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  I can't get the type ascription to work, but it seems the type parameter works, so +1.
  
  – Brian McCutchon
  Mar 24 at 6:43
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @BrianMcCutchon That's really surprising, thanks.
  
  – Alexey Romanov
  Mar 24 at 7:16
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Alexey Romanov - Thanks. Type parameter works. However, it puzzles me why implicit conversion doesn't. IntelliJ doesn't complain but maven compilation fails.
  
  – sooper
  Mar 25 at 0:57
  

  
  
  
  

add a comment | 

3

The problem is that the inferred type for Person.getClass is not the one you want. You need to specify the expected type, and this can be done by an explicit type parameter

registry.registerClasses(List[Class[_]](Person.getClass).asJava)

(I don't understand why type ascription doesn't work here:

registerClasses(List(Person.getClass: Class[_]).asJava)

type mismatch;
 found : java.util.List[Class[_$2]] where type _$2
 required: java.util.List[Class[_]]
Note: Class[_$2] <: Class[_], but Java-defined trait List is invariant in type E.
You may wish to investigate a wildcard type such as `_ <: Class[_]`. (SLS 3.2.10)

So far as I can tell it should.)

share|improve this answer

edited Mar 24 at 7:15

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  I can't get the type ascription to work, but it seems the type parameter works, so +1.
  
  – Brian McCutchon
  Mar 24 at 6:43
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @BrianMcCutchon That's really surprising, thanks.
  
  – Alexey Romanov
  Mar 24 at 7:16
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Alexey Romanov - Thanks. Type parameter works. However, it puzzles me why implicit conversion doesn't. IntelliJ doesn't complain but maven compilation fails.
  
  – sooper
  Mar 25 at 0:57
  

  
  
  
  

add a comment | 

The problem is that the inferred type for Person.getClass is not the one you want. You need to specify the expected type, and this can be done by an explicit type parameter

registry.registerClasses(List[Class[_]](Person.getClass).asJava)

(I don't understand why type ascription doesn't work here:

registerClasses(List(Person.getClass: Class[_]).asJava)

type mismatch;
 found : java.util.List[Class[_$2]] where type _$2
 required: java.util.List[Class[_]]
Note: Class[_$2] <: Class[_], but Java-defined trait List is invariant in type E.
You may wish to investigate a wildcard type such as `_ <: Class[_]`. (SLS 3.2.10)

So far as I can tell it should.)

share|improve this answer

edited Mar 24 at 7:15

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363

registry.registerClasses(List[Class[_]](Person.getClass).asJava)

registerClasses(List(Person.getClass: Class[_]).asJava)

type mismatch;
 found : java.util.List[Class[_$2]] where type _$2
 required: java.util.List[Class[_]]
Note: Class[_$2] <: Class[_], but Java-defined trait List is invariant in type E.
You may wish to investigate a wildcard type such as `_ <: Class[_]`. (SLS 3.2.10)

share|improve this answer

edited Mar 24 at 7:15

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363

answered Mar 24 at 6:20

Alexey RomanovAlexey Romanov

113k26218363