Fixing java.lang.ClassCastException in Hibernate Java

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The Problem

Imagine you have an entity class named VendorPrioritizedData, which represents a table in your database. Here’s a quick glance at its structure:

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When executing a native query to fetch data from the database, you might do something like this:

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Later, when you loop through the results and attempt to cast them to VendorPrioritizedData:

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You encounter a ClassCastException that looks like this:

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This error indicates that Hibernate is returning an array of objects instead of instances of VendorPrioritizedData.

Solution

To fix this issue, you need to explicitly tell Hibernate what type of objects you want your query to return. Follow these steps:

Step 1: Modify the Query

Change your query to specify the expected class for the results:

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Step 2: Iterate Through the Results Properly

Since we've modified the query to return a list of VendorPrioritizedData, you won’t get a ClassCastException anymore when iterating through fsFFDB:

[[See Video to Reveal this Text or Code Snippet]]

Summary

Understanding the Error: The ClassCastException occurs because Hibernate returns an array of objects from a native query unless specified otherwise.

Solution: Use the class type in your createNativeQuery method to inform Hibernate of the expected outcome.