Re: Using == on strings

[Michael Glavassevich]

Hello Dave,

If you've been looking through the source code you'll notice that in many places we compare strings by reference instead of calling equals. For performance reasons Xerces keeps a table of unique strings for XML names (elements, attributes, entities, etc...) and namespace names (URIs). These strings have all been internalized (by calling String.intern()) so unique references for names and namespace names are passed through the parser's components. Methods which are part of the public API cannot take advantage of this because a user may pass a reference to some other string object, however this method is not part of the DOM API. I did a search for references to this method using Eclipse and it seems that it's not being called anywhere.

Thanks.

"Dave Brosius" <[EMAIL PROTECTED]> wrote on 07/07/2004 10:29:47 PM:

> I ran across this in org.apache.xerces.dom.DeferredDocumentImpl
>  
> Shouldn't this be
>  
>             if (getChunkValue(fNodeName, achunk, aindex).equals( name)) {
>  
> ?
>  
>
>     public String getAttribute(int elemIndex, String name) {
>         if (elemIndex == -1 || name == null) {
>             return null;
>         }
>         int echunk = elemIndex >> CHUNK_SHIFT;
>         int eindex = elemIndex & CHUNK_MASK;
>         int attrIndex = getChunkIndex(fNodeExtra, echunk, eindex);
>         while (attrIndex != -1) {
>             int achunk = attrIndex >> CHUNK_SHIFT;
>             int aindex = attrIndex & CHUNK_MASK;
>             if (getChunkValue(fNodeName, achunk, aindex) == name) {
>                 return getChunkValue(fNodeValue, achunk, aindex);
>             }
>             attrIndex = getChunkIndex(fNodePrevSib, achunk, aindex);
>         }
>         return null;
>     }

Michael Glavassevich
XML Parser Development
IBM Toronto Lab
E-mail: [EMAIL PROTECTED]
E-mail: [EMAIL PROTECTED]