Platform.getClassForName

I suspect it has to do with the class being in the default package, as they're often treated specially. What happens if you put the class in a package?

On 2012-02-12 12:40 PM, "Mark_Grand" <mgrand@markgrand.com> wrote:

I am having trouble getting GetClassForName to find classes that I
have defined, but it can find classes from java.lang.  What am I doing
wrong.

Here is a simple example of my problem:

scala> import scala.compat.Platform
import scala.compat.Platform

scala> class Foo{}
defined class Foo

scala> val f = new Foo
f: Foo = Foo@171fcdde

scala> f.getClass().getName()
res0: java.lang.String = Foo

scala> Platform.getClassForName("Foo")
java.lang.ClassNotFoundException: Foo
       at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:
301)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
       at java.lang.Class.forName0(Native Method)
       at java.lang.Class.forName(Class.java:169)
       at scala.compat.Platform$.getClassForName(Platform.scala:57)
       at .<init>(<console>:9)
       at .<clinit>(<console>)
       at .<init>(<console>:11)
       at .<clinit>(<console>)
       at $print(<console>)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:
39)
       at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25)
       at java.lang.reflect.Method.invoke(Method.java:597)
       at scala.tools.nsc.interpreter.IMain
$ReadEvalPrint.call(IMain.scala:704)
       at scala.tools.nsc.interpreter.IMain$Request$$anonfun
$14.apply(IMain.scala:920)
       at scala.tools.nsc.interpreter.Line$$anonfun$1.apply$mcV
$sp(Line.scala:43)
       at scala.tools.nsc.io.package$$anon$2.run(package.scala:25)
       at java.lang.Thread.run(Thread.java:662)


scala> Platform.getClassForName("java.lang.Math")
res2: java.lang.Class[_] = class java.lang.Math

The original problem was with a class in a package. The full name of that class is com.peppyandcheap.hytaps.model.datatype.HTextI presented a simplified example to keep my question short.

On Sun, Feb 12, 2012 at 1:02 PM, Tom Switzer <thomas.switzer@gmail.com> wrote:

I suspect it has to do with the class being in the default package, as they're often treated specially. What happens if you put the class in a package?

On 2012-02-12 12:40 PM, "Mark_Grand" <mgrand@markgrand.com> wrote:

I am having trouble getting GetClassForName to find classes that I
have defined, but it can find classes from java.lang.  What am I doing
wrong.

Here is a simple example of my problem:

scala> import scala.compat.Platform
import scala.compat.Platform

scala> class Foo{}
defined class Foo

scala> val f = new Foo
f: Foo = Foo@171fcdde

scala> f.getClass().getName()
res0: java.lang.String = Foo

scala> Platform.getClassForName("Foo")
java.lang.ClassNotFoundException: Foo
       at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:
301)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
       at java.lang.Class.forName0(Native Method)
       at java.lang.Class.forName(Class.java:169)
       at scala.compat.Platform$.getClassForName(Platform.scala:57)
       at .<init>(<console>:9)
       at .<clinit>(<console>)
       at .<init>(<console>:11)
       at .<clinit>(<console>)
       at $print(<console>)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:
39)
       at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25)
       at java.lang.reflect.Method.invoke(Method.java:597)
       at scala.tools.nsc.interpreter.IMain
$ReadEvalPrint.call(IMain.scala:704)
       at scala.tools.nsc.interpreter.IMain$Request$$anonfun
$14.apply(IMain.scala:920)
       at scala.tools.nsc.interpreter.Line$$anonfun$1.apply$mcV
$sp(Line.scala:43)
       at scala.tools.nsc.io.package$$anon$2.run(package.scala:25)
       at java.lang.Thread.run(Thread.java:662)


scala> Platform.getClassForName("java.lang.Math")
res2: java.lang.Class[_] = class java.lang.Math

--
Mark Grand
(404)925 8265
Vision, Values, Verve:
* Visualize the end game with
* Values to lead ethically and with purpose; and
* Verve to execute with shameless audacity.

This is interesting...
Given this little program:class Foo                                                                                                                                                                                                                                                                               object TestClass {                                                                                                                            def main(args: Array[String]) {                                                                                                               try {                                                                                                                                         // this fails                                                                                                                               val cls = scala.compat.Platform.getClassForName("Foo")                                                                                      println(cls.getName)                                                                                                                      } catch {                                                                                                                                     // so we get a stack trace here                                                                                                             case e: Exception => e.printStackTrace                                                                                                    }                                                                                                                                           // this succeeds                                                                                                                            val cls = Class.forName("Foo")                                                                                                              println(cls.getName)                                                                                                                      }                                                                                                                                         }                                                                                                                                             
Produces the following results:$ scala TestClassjava.lang.ClassNotFoundException: Foo at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at scala.compat.Platform$.getClassForName(Platform.scala:57) at TestClass$.main(TestCls.scala:6) at TestClass.main(TestCls.scala) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at scala.tools.nsc.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:78) at scala.tools.nsc.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:24) at scala.tools.nsc.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:88) at scala.tools.nsc.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:78) at scala.tools.nsc.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:101) at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:33) at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:40) at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:56) at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:80) at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:89) at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)Foo

Even more interesting, if you compile it with -optimize, both calls succeed:
$ scalac -optimize TestCls.scala$ scala TestClassFooFoo
Probably because Platform.getClassForName as the @inline annotation, so with the -optimize flag the call in Platform to getClassForName is inlined into the TestClass object as Class.forName, while without -optimize the call to Class.forName is made from the Platform object.
Looks like a bug to me.

https://issues.scala-lang.org/browse/SI-5457

Strange

I tested with 2.9.1.final and 2.10.0-M1 compilers and they both work

Only in the REPL it doesn't work.

But I have Windows 7

On 12 feb, 19:48, Erik Engbrecht wrote:
> https://issues.scala-lang.org/browse/SI-5457

It probably has something to do with differences in the script that is used to run Scala.  If I use this command:$ java -classpath .:/usr/local/share/scala/lib/scala-library.jar TestClass

Then it works.