This is an excerpt from the Scala Cookbook (partially modified for the internet). This is one of the shorter recipes, Recipe 6.2, “The Scala equivalent of Java’s
When an API requires that you pass in a Class, you’d call
.class on an object in Java, but that doesn’t work in Scala.
Use the Scala
classOf method instead of Java’s
.class. The following example shows how to pass a class of type
TargetDataLine to a method named
val info = new DataLine.Info(classOf[TargetDataLine], null)
By contrast, the same method call would be made like this in Java:
// java info = new DataLine.Info(TargetDataLine.class, null);
classOf method is defined in the Scala
Predef object and is therefore available in all classes without requiring an import.
This approach also lets you begin with simple reflection techniques. The following REPL example demonstrates how to access the methods of the
scala> val stringClass = classOf[String] stringClass: Class[String] = class java.lang.String scala> stringClass.getMethods res0: Array[java.lang.reflect.Method] = Array(public boolean java.lang.String.equals(java.lang.Object), public java.lang.String (output goes on for a while ...)
- Oracle’s “Retrieving Class Objects” document
- The Scala Predef object
The Scala Cookbook
This tutorial is sponsored by the Scala Cookbook, which I wrote for O’Reilly:
You can find the Scala Cookbook at these locations:
There’s just one person behind this website; if this article was helpful (or interesting), I’d appreciate it if you’d share it. Thanks, Al.