import java.util.Collections;
import java.util.Iterator;
import java.util.TreeSet;

public class IteratorTest {

	public static void main(String[] args) {
		TreeSet<String> set = new TreeSet<String>();
		for (int i = 0; i < 20; i++) {
			set.add(new Integer(i).toString());
		}

		for (Iterator<String> it = set.iterator(); it.hasNext();) {
			String s = it.next();
			if (s.equals("15"))
				it.remove();
			System.out.println(s); // "15" noch enthalten
		}

		Iterator<String> iter = set.iterator();
		while (iter.hasNext()) {
			String s = iter.next();
			// if(s.equals("15")) set.remove(s); // ConcurrentModificationException
			iter.remove();
			System.out.println(s); // "15" entfernt
		}
	}
}