Difference Betwixt Hashset Together With Hashmap Inwards Java

HashSet together with HashMap inwards Java
HashSet vs HashMap is a classical Java Collection interview question which focuses on What are differences betwixt HashSet together with HashMap inwards damage of features, usage, together with performance. If yous are inwards Java programming fifty-fifty for a yr or so, yous are probable to live on familiar amongst What is HashSet inwards Java together with What is HashMap inwards Java, these 2 are nigh pop collection classes. Despite beingness hash based collection HashSet and HashMap are unlike to each other because the underlying interface is different. HashSet implements Set interface via extending AbstractSetclass together with HashMap implements Map interface. Before seeing differences betwixt let's come across what is common betwixt HashSet together with HashMap inwards Java:

Similarities on HashMap together with HashSet inwards Java

Here are some of the mutual materials betwixt both of them:

1) Both HashMap and HashSet are a hash based collection inwards Java.
2) Both HashMap and HashSet are non synchronized and tin flame non live on shared betwixt multiple threads.
3) Iterator returned yesteryear HashMap's keySet() together with HashSet are fail-fast together with they ConcurrentModificationException if they discovery whatever structural modify inwards Collection.

4) Both HashMap together with HashSet provided constant fourth dimension performance for basic operations similar put(), get() etc.
5) Both HashSet together with HashMap allows naught values.

Differences betwixt HashSet together with HashMap inwards Java

After seeing similarities on HashMap and HashSet, instantly let's come across some deviation betwixt them :

1) The kickoff together with nigh pregnant deviation betwixt HashMap together with HashSet is that HashMap is an implementation of Map interface spell HashSet is an implementation of Set interface, which way HashMap is a cardinal value based data-structure together with HashSet guarantees uniqueness yesteryear non allowing duplicates.In reality, HashSet is a wrapper some HashMap inwards Java, if yous hold back at the code of add(E e) method of HashSet.java yous volition come across next code :

public boolean add(E e) {
        render map.put(e, PRESENT)==null;
}

where it's putting  Object into a map every bit cardinal together with value is a finally object PRESENT which is a dummy.

2) The minute deviation betwixt HashMap and HashSet is that nosotros purpose add() method to seat elements into Set simply nosotros purpose put() method to insert cardinal together with value into HashMap inwards Java.

3) HashSet allows alone 1 naught key, simply HashMap tin flame allow 1 naught cardinal + multiple naught values.

That's all on the difference betwixt HashSet together with HashMap inwards Java. In summary HashSet together with HashMap are 2 unlike type of Collection 1 beingness Set together with other beingness Map.

Further Learning
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