Scala Java Converters Example

August 29, 2021 Post a Comment

Heres the Scala source code for that class. Param metadataCache the metadata cache which will be used to fetch metadata.

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So collections are never copied when converting between Java and Scala.

Scala java converters example. ScalaJava integration problem. These are implicit converters from all Java primitives to Scala equivalents. The use of javautilList and the asScala and asJava converters.

For a more modern approach see my tutorial How to convert a Java Map to a Scala Map using JavaConverters. Return a map from each system stream to its metadata. Crafted by highly motivated engineers at Koofr and hopefully making your day.

Scala Programming Model. Private static Map. Import scalacollectionJavaConversions_ val myScalaMap myJavaMapmapValues_toSet Calling mapValues will trigger an implicit conversion from the java Map to a scala Map and then calling toSet on the java collection with implicitly convert it to a scala.

Param streamsToMonitor the set of system streams for which the metadata is needed. Thats because Predef includes the following implicit. I started with a very simple Scala class definition which I named Main and stored in a file named Mainscala.

There is one method for each Java primitive type boolean byte char double float int long and short. A second key is knowing that the JavaConversions object is deprecated and you should use JavaConverters instead of JavaConversions. You can use scalacollectionJavaConversions to implicitly convert between Java and Scala.

Handles scala-java conversions. These examples are extracted from open source projects. A simple Scala class.

These are all necessary because the built-in Lambda serializer doesnt understand native Scala types. Java to Scala converter source code is available on Github under MIT license. I dont want you to see my code.

As an example of the two-way conversions shown in Table 17-1 the JavaConversions object provides methods that convert between a Java List and a Scala BufferThe asScalaBuffer method converts a Java List to a Scala Buffer and bufferAsJavaList converts in the opposite direction from a Buffer to a List. For example when calling a Java method that expects a javalangInteger you are free to pass it a scalaInt instead. You can notice this in code above.

In Scala 213 the JavaConverters class was moved to scala. The JavaConversions object in Scala has been deprecated. Scala idioms are so dramatically different from Java that even well-written Java code would turn into poorly written Scala code.

The following examples show how to use scalacollectionJavaConverters. The original answer with JavaConversions. Going from Scala collections to Java collections.

The returned Java Map is backed by the provided Scala Map and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa. Assert but also several implicit conversions. Lets have a look at an example.

Towards the end of this tutorial Ill also convert the Scala class files back to Java source code using a tool named jad which is a Java decompiler. ScalacollectionimmutableMap is aliased to Map and methods eg. So far youve looked primarily at.

I started with a very simple Scala class definition which I named Main and stored in a file named Mainscala. You can vote up the ones you like or vote down the ones you dont like and go to the original project or source file by following the links above each example. Heres the Scala source code for that class.

An interesting property is that if you do a round-trip conversion from say a Java type to its corresponding Scala type and back to the same Java type you end up with the identical collection object you have started with. The key there is knowing that importing the JavaConverters object creates a method named asScala on the Java Map and that method creates a Scala Map from the Java Map. Towards the end of this tutorial Ill also convert the Scala class files back to Java source code using a tool named jad which is a Java decompiler.

A simple Scala class. Java to Scala converter is created with Play framework and Scalagen library. If the Scala Map was previously obtained from an implicit or explicit call of asMapjavautilMap then the original Java Map.

You need to share a Scala map with a Java method or access a Java map in Scala code. The implicitly imported object scalaPredef declares several aliases to frequently used types eg. Writing Lambda functions in Scala requires dealing with some Javaisms at the points of entry and exit.

Kdgregory Mar 20 10 at 1943 Alex R - I dont know how much Java code you have but if its only a few thousand classes youre going to be better off converting it.

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