Intellij IDEA has had Java to Scala conversion built into it for a while (as well as Java to Kotlin, Jetbrain's new JVM Scala-like language). I'm not sure how J

Intellij IDEA has had Java to Scala conversion built into it for a while (as well as Java to Kotlin, Jetbrain's new JVM Scala-like language). I'm not sure how Jetbrain's tool compares to the one in the link above, but the conversion result in Intellij varies by how complicated and dependent the code is on other packages/libraries. Converting an entire class file tends to work out much better than a single method. I initially used it to convert some Android code in Java to Scala, but much of the time you have to end up rewriting that as well, since it's generally results in very non-idiomatic Scala code. Still useful for someone learning Scala though as others have pointed out. The Scala plugin is free though and comes with the community edition of Intellij for anyone wanting to try it out. Basically you just copy/paste some Java code from the current project into a Scala file or right click on the Java file and select "convert."