collections in java

The Treemap is a component of the Java Collections Framework that implements the SortedMap interface. It keeps its elements ordered according to the natural ordering of keys or a defined comparator.

HashSet is a Java Collections Framework class that implements the Set interface. It gives a collection with no duplicate elements and no set order for its elements. HashSet is built on a hash table data structure, which allows it to add, remove, and search for elements in constant time (O(1)).

In Java, the ArrayList class implements the List interface as a resizable array. It offers dynamic arrays that can expand or contract in size as needed. ArrayLists are a component of the Java Collections Framework and provide a variety of methods for modifying the elements contained in them.