Generic Inner class doubt

[Sergio Tridente]

Hi,

I am studying to get strong in the use of Generics and I came into a doubt regarding the use of generic inner classes:

This is my test program:

class One {}
class Two extends One {}
 
class Outer<T> {
private T myPrivate;
 
Outer(Class<? extends T> type) throws InstantiationException, IllegalAccessException {
this.myPrivate = type.newInstance();
}

public void yieldClass() {
System.out.println("Outer--> " + this.myPrivate.getClass().getName());
}
 
class Inner<S extends T> {
private S myInnerPrivate;
private T myOuterPrivate;

Inner(Class<? extends S> type) throws InstantiationException, IllegalAccessException {
this.myInnerPrivate = type.newInstance();
this.myOuterPrivate = Outer.this.myPrivate;
}

public void yieldClass() {
System.out.println("Inner--> " + this.myInnerPrivate.getClass().getName() + " - " + this.myOuterPrivate.getClass().getName());
}
}
}
 
public class GenericInner {
public static void main(String[] args) throws InstantiationException, IllegalAccessException {
Outer<One> o1 = new Outer<One>(One.class); //1
o1.yieldClass();
 
Outer<One> o2 = new Outer<One>(Two.class); //2
o2.yieldClass();
 
Outer<One>.Inner<Two> i1 = o1.new Inner<Two>(Two.class); //3
i1.yieldClass();
 
Outer<One>.Inner<? extends One> i2 = o2.new Inner<Two>(Two.class); //4
i2.yieldClass();
}
}

The code compiles and runs as expected for //1 and //2.

These are the compiler messages for //3:

GenericInner.java:38: type parameter Two is not within its bound
                Outer<One>.Inner<Two> i1 = o1.new Inner<Two>(Two.class); //3
                                 ^
GenericInner.java:38: type parameter Two is not within its bound
                Outer<One>.Inner<Two> i1 = o1.new Inner<Two>(Two.class); //3
                                                        ^

This one is for //4:

GenericInner.java:41: type parameter Two is not within its bound
                Outer<One>.Inner<? extends One> i2 = o2.new Inner<Two>(Two.class
); //4
                                                                  ^

What is worng with those lines? How can I instantiate my inner class?

I know this problem may be beyond the actual exam level, but i would really appreciate if someone could point me to the right direction.

Thank you very much.

[Brian Spindler]

Code compiles fine on my machine (JDK 1.5.0_08) and produces the following output:

Outer--> One
Outer--> Two
Inner--> Two - One
Inner--> Two - Two

[Sergio Tridente]

Strange. I am using JDK 1.5.0_11 (+ console) and still getting the same errors.

But, it certainly did work this morning at home where I was using Eclipse and JDK 1.5.0_10. Are you using Eclipse too? Or is this an 'issue' with JDK 1.5.0_11?

[Brian Spindler]

Using eclipse too.

[John Stone]

in eclipse fine, in command line errors.
I have javac 1.6.0_01, in eclipse using "compiler compliance 5.0", in console "-source 1.5"

[John Stone]

found this:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6557954

[Sergio Tridente]

Thank you John and Brian.
[ May 30, 2007: Message edited by: Sergio Tridente ]