How is key comparison performed when storing data in a HashMap?

In a HashMap, key comparison usually occurs using the equals() method (in Java) or an equivalent, which is defined for the key type. When adding or searching for an element, the hash code of the key is first computed to determine the bucket, and then among the elements in that bucket, key comparison is performed using equals() for an exact match.

For example, in Android, HashMap uses:

• hashCode() to compute the hash of the key
• equals() to compare keys within the same bucket

This allows for efficient element retrieval and proper collision handling.

Java example:

HashMap<String, Integer> map = new HashMap<>();
map.put("key", 1);
Integer value = map.get("key"); // first computes hashCode(), then uses equals() for search

Thus, key comparison involves calling equals() on keys that have the same hash code.