> -----Original Message-----
> From: A mailing list for Enterprise JavaBeans development
> [mailto:[EMAIL PROTECTED]] On Behalf Of Juan Pablo Lorandi
> public boolean equals(Object obj)
> {
> AlbumTrackBeanPK pkObj=(AlbumTrackBeanPK)obj;
> return (albumId==(pkObj.albumId) &&
> trackId==(pkObj.trackId) );
> }
This is a dangerous implementation that can throw ClassCastException.
Here is a safer one:
public boolean equals(Object other) {
if (other == this) return true;
if (null == other) return false;
if (other.hashCode() != hashCode()) return false;
try {
TrackBeanPK other2 = (TrackBeanPK) other;
return this.albumID.equals(other2.albumID) &&
this.trackId.equals(other2.trackId);
}
catch(ClassCastException ex) {
return false;
}
}
Note that this implementation is optimized in several ways:
- Check for obvious cases first
- Assume that in most cases, the two objects being compared will be of
the same class
> public int hashCode()
> {
> try
> {
> long crcKey = -1;
> java.io.ByteArrayOutputStream bos = new
> java.io.ByteArrayOutputStream();
> java.io.ObjectOutputStream oos = new
> java.io.ObjectOutputStream(bos);
> oos.writeObject(this);
> oos.flush();
> java.util.zip.Adler32 adl32 = new java.util.zip.Adler32();
> adl32.update(bos.toByteArray());
> crcKey = adl32.getValue();
> return (int)(crcKey ^ (crcKey >> 32));
> } catch (java.io.IOException ioEx)
> {
> return -1;
> }
>
> }
> }
Also, note that using ObjectOutputStream for hashcode() might be
serializing more than is needed (e.g. FatKey pattern).
--
C�dric
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