Closing a java.util.Iterator

Question

I\'ve implemented a custom java.util.Iterator using a resource that should be released at the end using a close() method. That resource could

Answer 1

Just define your own sub-interface of Iterator that includes a close method, and make sure you use that instead of the regular Iterator class. For example, create this interface:

import java.io.Closeable;
import java.util.Iterator;

public interface CloseableIterator extends Iterator, Closeable {}

And then an implementation might look like this:

List someList = Arrays.asList( "what","ever" );
final Iterator delegate = someList.iterator();
return new CloseableIterator() {
    public void close() throws IOException {
        //Do something special here, where you have easy
        //access to the vars that created the iterator
    }

    public boolean hasNext() {
        return delegate.hasNext();
    }

    public String next() {
        return delegate.next();
    }

    public void remove() {
        delegate.remove();
    }
};