How can I implement the Iterable interface?

Question

Given the following code, how can I iterate over an object of type ProfileCollection?

public class ProfileCollection implements Iterable {    
    private Ar         


        

Answer 1

First off:

public class ProfileCollection implements Iterable<Profile> {

Second:

return m_Profiles.get(m_ActiveProfile);

Answer 2

Iterable is a generic interface. A problem you might be having (you haven't actually said what problem you're having, if any) is that if you use a generic interface/class without specifying the type argument(s) you can erase the types of unrelated generic types within the class. An example of this is in Non-generic reference to generic class results in non-generic return types.

So I would at least change it to:

public class ProfileCollection implements Iterable<Profile> { 
    private ArrayList<Profile> m_Profiles;

    public Iterator<Profile> iterator() {        
        Iterator<Profile> iprof = m_Profiles.iterator();
        return iprof; 
    }

    ...

    public Profile GetActiveProfile() {
        return (Profile)m_Profiles.get(m_ActiveProfile);
    }
}

and this should work:

for (Profile profile : m_PC) {
    // do stuff
}

Without the type argument on Iterable, the iterator may be reduced to being type Object so only this will work:

for (Object profile : m_PC) {
    // do stuff
}

This is a pretty obscure corner case of Java generics.

If not, please provide some more info about what's going on.