How to Implement a Custom Hash function for Keys in a HashMap in Java?

In Java, HashMap is the data structure that implements the Map interface. This is used to save the data in the form of key-value pairs. In this article, we will learn how to implement a Custom Hash function for keys in a HashMap in Java.

In Java, implementing the custom hash function for keys in a HashMap requires overriding the hashcode() method in the class of the keys to correctly identify and store the keys in the HashMap. The hashcode() method generates a hash code for an object, which is used by HashMap.

Program to Implement a Custom Hash Function For Keys in a HashMap

Below is the Program to Implement a Custom Hash Function For Keys in a HashMap:

{key1=Java, key2=JavaScript, key3=Java}
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Explanation of the Program:

• We have defined a HashMap that uses custom keys and stores string values.
• Each CustomKey is associated with a string, and the HashMap is populated with three key-value pairs.
• Then the CustomKey class overrides the hashCode(), equals(), and toString() methods.
• This identified that keys are correctly identified and stored in the HashMap.
• After that, it retrieves the values associated with each key from the HashMap and prints them.