The following code throws an ArrayIndexOutOfBoundsException, because remove disturbes the iterator state.

import java.util.*;

public class test
{
  public static void main(String[] args) throws Exception
  {
    IdentityHashMap m = new IdentityHashMap();
    for(int i = 0; i < 10; i++)
    {
      m.put("foo" + i, "bar" + i);
    }
    Iterator iter = m.values().iterator();
    while(iter.hasNext())
    {
      System.out.println(iter.next());
      iter.remove();
    }
  }
}