how to convert List[java.util.Map] to List[Map]

Question

how to convert List[java.util.Map] to List[Map] in scala?

oldList:

List[java.util.Map[String,String]]

wantedList:

List[Map[String,String]]

should i new a List[Map] and loop the oldList ?

thanks!

Pooya · Accepted Answer · 2013-07-23 06:30:01Z

2

Use converter methods in Scala collection package. and this is a sample to demonstrate how to convert:

import scala.collection.JavaConverters._

oldList: List[java.util.Map[String,String]]

wantedList= oldList.asScala

Edited:

as Vladimir Matveev mentioned

wantedList=oldList.map(_.asScala)

edited Jul 23, 2013 at 6:30

answered Jul 23, 2013 at 5:43

Pooya

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1 Comment

Vladimir Matveev Over a year ago

The overall direction (usage of JavaConverters) is correct, but you have to map through the list with asScala, not just call this method on the list: oldList.map(_.asScala)

Mikhail Aksenov · Accepted Answer · 2013-07-23 05:59:07Z

0

You could use scala.collection.JavaConversions static methods. This one adds implicit conversions from standard Java collections and allows you to perform things like this (let's assume we have already opened REPL and imported scala.collection.JavaConversions._):

scala > x
res1: java.util.HashMap[String,String] = {1=2}

scala> x.toMap
res2: scala.collection.immutable.Map[String,String] = Map(1 -> 2)

You could solve your particular problem as following:

res5: list: List[java.util.HashMap[String, String]] = ()
scala > list.map(e => e.toMap)
res6: List[scala.collection.immutable.Map[String,String]] = ()

edited Jul 23, 2013 at 5:59

answered Jul 23, 2013 at 5:53

Mikhail Aksenov

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Comments

4lex1v · Accepted Answer · 2013-07-23 17:08:47Z

0

JavaConverters were deprecated since Scala 2.9.0 and removed in Scala 2.11-M1 you should not use them. Instead there is a package scala.collection.convert with a module WrapAsScala. It has an implicit convertion dictionaryAsScalaMap

edited Jul 23, 2013 at 17:08

answered Jul 23, 2013 at 7:06

4lex1v

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5 Comments

sourcedelica Over a year ago

There were a few members of JavaConverters that were deprecated but JavaConverters in general is not deprecated.

4lex1v Over a year ago

@sourcedelica JavaConverters as you can see all members were deprecated

sourcedelica Over a year ago

Those internal members were deprecated but everything that it inherits from DecorateAsJava and DecorateAsScala were not. The JavaConverters object itself was not, and import JavaConverters._ still works as it used to. Eg. you can do jmap.asScala.

4lex1v Over a year ago

@sourcedelica That was done for migration purposes and backward compatibility in Scala 2.11-M1 they were removed.

sourcedelica Over a year ago

Here is the nightly API docs: scala-lang.org/archives/downloads/distrib/files/nightly/docs/…

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