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Conversely, the assumption that two classes deriving from the same codebase are the same is error prone. Although this assumption is commonly observed to be true in desktop applications, it is typically not the case with J2EE servlet containers. The containers can use different class loader instances to deploy and recall applications at runtime without having to restart the JVM. In such situations, two objects whose classes come from the same codebase could appear to the JVM to be two different classes. Also note that the equals() method might not return true when comparing objects originating from the same codebase.
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