Menu
When we have equals(), compareTo() methods why there is a hashcode() method in Java?
And in case if we use HashTable we have to override hashcode() method, Is there any special reason except fast accessing of random keys? If we override the hashcode() method what would be the probable implementation ?
How Java ensures object uniqueness in memory?
Hashcodes are typically used to enhance the performance of large collections of data.
In hashing we calculate hash code. it's an additional task. When we do additional operation for each object that is added to a collection. How the performance gets improved?
585
No, it will not allow duplicates. hashTable. put(key, value); If key is already present, existing value will be overridden by the new value for a given key and returns the old value.
If multiple objects return the same value from hashCode(), it means that they would be stored in the same bucket. If many objects are stored in the same bucket it means that on average it requires more comparison operations to look up a given object.
Whenever two different objects have the same hash code, we call this a collision. A collision is nothing critical, it just means that there is more than one object in a single bucket, so a HashMap lookup has to look again to find the right object.
The equals() and hashcode() are the two important methods provided by the Object class for comparing objects. Since the Object class is the parent class for all Java objects, hence all objects inherit the default implementation of these two methods.
You must always override equals and hashCode in tandem, to satisfy their interdependent contracts. A class which implements them contradictorily is simply broken and unacceptable under even the minimum software engineering standards.
As to why one would ever use the hashtable data structure: because it is the fastest option around for random-access key-value storage.
70
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
