How is the comparison of keys and values within a HashMap data structure performed?

In Java, the HashMap data structure uses the hashCode() and equals() methods to compare keys.

• When adding or searching for an element, the hash code of the key is first calculated using the hashCode() method. This helps determine the bucket in the hash table.
• If there are multiple elements in the bucket (collision), the equals() method is called for each to perform an exact comparison of the keys.

Therefore, for the correct operation of HashMap, it is important that key classes properly override both methods:

• hashCode() should return the same value for equal objects.
• equals() should correctly compare objects for equality.

Values in HashMap are usually compared only when necessary (e.g., during search), but keys are always used to determine position and uniqueness.