Coding⏱️ 3 min read📅 2026-06-04

How to Fix: Overriding the java equals() method - not working?

Understanding why overriding the equals() method is crucial in object-oriented programming.

Quick Answer: Overriding the equals() method ensures that objects are compared correctly, preventing unexpected behavior and bugs.

The Java equals() method is used to compare two objects for equality. However, when overriding this method in a custom class, it's not uncommon to encounter issues due to the way Java handles object comparison.

This particular issue can be frustrating because it may cause unexpected behavior or errors in your code, especially when working with complex data structures like lists or collections.

🛑 Root Causes of the Error

  • The primary reason for this issue is that the equals() method is not overridden correctly. When you override the equals() method in a custom class, you must also override the hashCode() method to ensure correct behavior.
  • Another possible cause could be using the '==' operator instead of the '.equals()' method when comparing objects.

🔧 Proven Troubleshooting Steps

Overriding the equals() and hashCode() methods

  1. Step 1: Step 1: In your custom class, override the equals() method by comparing the fields that are relevant to equality. For example, if you're comparing two Book objects based on their title and author, you would compare these fields in the equals() method.
  2. Step 2: Step 2: Along with overriding the equals() method, also override the hashCode() method. The hashCode() method should return a hash code value for the object, which is an integer that represents the object's identity.
  3. Step 3: Step 3: After making these changes, recompile your class and test it again to ensure that the issue is resolved.

Using the 'equals()' method correctly

  1. Step 1: Step 1: In your code, use the '.equals()' method instead of the '==' operator when comparing objects. This ensures that you're comparing the actual values of the objects rather than their memory locations.
  2. Step 2: Step 2: By using the '.equals()' method correctly, you can avoid issues related to overriding the equals() and hashCode() methods.

✨ Wrapping Up

To overcome this issue, make sure to override the equals() method correctly in your custom class, along with the hashCode() method if necessary. Additionally, use the '.equals()' method correctly when comparing objects in your code.

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