Explain the contract between the equals method and the hashCode method.

Question

Accepted Answer

The equals and hashCode methods are crucial for object comparison and storage in collections like HashMap and HashSet.

1. The equals method checks if two objects are logically equivalent.
2. The hashCode method returns an integer representation of an object's memory address.
3. If two objects are equal (equals returns true), their hashCode must also be the same.
4. If two objects have the same hashCode, they are not necessarily equal.
5. Failing to override hashCode when equals is overridden can lead to unexpected behavior in collections.

Accepted Answer

Two objects that are equal to each other will have the same hashcode.
Two objects that are not equal to each other may have the same hashcode but that is not considered a good and efficient implementation.
The hashcode of an object should not change unless the fields which are utilized in the equals method changes

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Explain the contract between the equals method and the hashCode method.

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