What is the use of hashCode in Java?

java hashcode
Vinoth Kumar picture Vinoth Kumar · Aug 25, 2010 · Viewed 172.2k times · Source

In Java, obj.hashCode() returns some value. What is the use of this hash code in programming?

Answer

aish picture aish · Feb 22, 2013

hashCode() is used for bucketing in Hash implementations like HashMap, HashTable, HashSet, etc.

The value received from hashCode() is used as the bucket number for storing elements of the set/map. This bucket number is the address of the element inside the set/map.

When you do contains() it will take the hash code of the element, then look for the bucket where hash code points to. If more than 1 element is found in the same bucket (multiple objects can have the same hash code), then it uses the equals() method to evaluate if the objects are equal, and then decide if contains() is true or false, or decide if element could be added in the set or not.

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