Generic method invocations with explicit type parameters

Question

If I interpret the JSR14 public draft spec (June 23, 2003) section 5.6 correctly the following method invocations with explicit type parameters should compile: package generics;
public class G121 {
  void f() {
    this.<String>f2();
    <String>f2(); // compilation error
    <String>f3(); // compilation error
  <T> void f2() {
  static <T> void f3() {
}but the class does not compile: jc -J-showversion generics\G121.javajava version "1.5.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta-b32c)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b32c, mixed mode)
generics\G121.java:6: illegal start of expression
    <String>f2(); // compilation error
            ^
generics\G121.java:8: illegal start of expression
    <String>f3(); // compilation error
            ^
2 errors
>A bug or do I miss something?

Answer 1

I get this error:
LineCount.java:104: cannot find symbol
symbol : method <java.io.File>sort(java.util.List<java.io.File>)
location: class java.util.Collections
Collections.<File>sort( list );
^
1 errorYou don't need the explicit type argument there, but anyway...
If you look at the docs for Collections.sort(List<T> list) you'll see it is declared as:
static <T extends Comparable<? super T>> void Collections.sort(List<T> list) Unfortunately, although File implements Comparable, it doesn't actually implement Comparable<File> or even Comparable<Object>, so I guess it can't satisfy the bound.
You can get it to compile by removing the explicit type argument and casting to the raw type List, but that's not very nice.
This seems like an oversight to me - File already has both int compareTo(Object o) and int compareTo(File pathname) so I don't see why it can't implement Comparable<File>. This isn't the only such case in the API though, so maybe I'm missing something.
Mark