Re: Yet another ConcurrentModificationException question

From:

Eric Sosman <Eric.Sosman@sun.com>

Newsgroups:

comp.lang.java.help

Date:

Tue, 19 Aug 2008 17:17:36 -0400

Message-ID:

<1219180631.27674@news1nwk>

Heiner K?cker wrote:

Andy Chambers schrieb

Apologies for asking about this FAQ. I have looked up the relevant
java tutorial but I just want to check my understanding with the
following example.

Iterator oIterator = m_oCollection.iterator();
while( oIterator.hasNext()) {
           Element oElement = (Element)oIterator.next();
           String sOIDValue =
oElement.getAttribute(oElement.getOIDKey());
           if( sOIDValue != null && sOIDValue.equals(sElementOID) ) {
               // We have a match
               return oElement;
           }
       }

If I know that neither getAttribute() or getOIDKey() can alter the
"structure" of m_oCollection, is it true to say that a
ConcurrentModificationException thrown from within the body of the
while loop above, *must* have been caused by another thread altering
the structure of m_oCollection?

So to prevent this from happening, I can make m_oCollection a
synchronized Vector (currently it is just a normal vector), and put
this while loop inside a synchronized block.

Use a for loop , no iterator.

     If you mean

    for (Object obj : m_oCollection) {
        Element oElement = (Element)obj;
        ...
    }

.... there *is* an Iterator, hidden by the syntax but present anyhow.
It's a bit like

    System.out.println("Hello, " + System.getProperty("user.name"));

.... where a StringBuilder is used even though you don't see it
mentioned in the source code.

--
Eric.Sosman@sun.com