Name: gm110360 Date: 08/06/2003


FULL PRODUCT VERSION :
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_01-b01)
Java HotSpot(TM) Client VM (build 1.4.1_01-b01, mixed mode)

FULL OPERATING SYSTEM VERSION :
Microsoft Windows 2000 [Version 5.00.2195]

A DESCRIPTION OF THE PROBLEM :
Concurrent modification exception is not thrown on the
second to last iteration of an iterator.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Compile and run the small test program -- it should
   die with concurrent modification exception. If the
   item removed from the list is anything but "c" it works.

EXPECTED VERSUS ACTUAL BEHAVIOR :
Expected a concurrent modification exception in this case:
Iterator iter = list.iterator();
while(iter.next()) {
   Object o = iter.next();
   if(2nd to last item in list) {
      list.remove(o); // <-- expected exception here!
   }
}

ERROR MESSAGES/STACK TRACES THAT OCCUR :
the problem is the lack of an exception

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.Iterator;
import java.util.ArrayList;
import java.util.List;
import java.util.Vector;

/**
 * @author Steven R Brandt
 */
public class CopyIterator {
    public void remove() {
        throw new Error("cannot remove from CopyIterator");
    }

    public static void main(String[] args) throws Exception {
        list.add(new ToyListener("a"));
        list.add(new ToyListener("b"));
        list.add(new ToyListener("c"));
        list.add(new ToyListener("d"));
        Iterator iter = list.iterator();
        while(iter.hasNext()) {
            ToyListener toy = (ToyListener)iter.next();
            toy.event();
            System.out.println(toy);
        }
    }
    static List list = new Vector();
    public static class ToyListener {
        String name;
        ToyListener(String name) {
            this.name = name;
        }
        public void event() {
            // this should cause a concurrent modification exception
            // if "a", "b", or "d" are used it will
            if(name.equals("c")) {
                list.remove(this);
            }
        }
        public String toString() {
            return "Toy: "+name;
        }
    }
}
---------- END SOURCE ----------

CUSTOMER WORKAROUND :
write your own iterator
(Incident Review ID: 180003)
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