I've blogged in the past about using the Apache Commons EqualsBuilder and HashCodeBuilder to write simpler equals() & hashCode() methods . My colleague recently blogged about a potential pitfall when using this approach , I'll summarise his findings here: Be VERY careful when you ask the HashCodeBuilder to generate the resulting hashcode value: Make sure you call builder.toHashCode() rather than builder.hashCode() The first correctly generates a hashcode value based on the objects that you have added to the builder, the second gives you the hashcode of the builder object itself - definitely not the value you would be expecting (and would be a sure fire way to lose your objects in a Collection )... Technorati Tags: Java , Apache Commons , HashCodeBuilder , hashCode , Andrew Beacock
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