What is the hashCode method in Java?

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The hashCode method is an inbuilt method that returns the integer hashed value of the input value.

Here are a few key concepts to remember:

  • Multiple invocations of the hashCode must return the same integer value within the execution of a program unless the Object used within the equals method changes. The integer value need not be the same for the next implementation.
  • If two or more objects are equal according to the equals method, then their hashes should be equal too.
  • If two or more objects are not equal according to the equals method, then their hashes can be equal or unequal.

Remember: If you override the equals method, it is crucial to override the hash method as well.

Code

The following code shows how to declare a hashCode:

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