What is the TreeSet class?

The TreeSet class extends the AbstractSet class. It implements the SortedSet, Cloneable, and Serializable interfaces. It also implements the Set interface, backed by a TreeMap instance. This class guarantees that the sorted set will be in ascending element order, sorted according to the natural order of the elements, or by the comparator provided at set creation time, depending on which constructor is used. The following are the constructors of TreeSet:

TreeSet()
TreeSet(Collection c)
TreeSet(Comparator c)
TreeSet(SortedSet s)

The elements that are going to be inserted into the TreeSet must implement the Comparable interface. If a user attempts to add an element to the set that violates this constraint, the add(Object) call will throw a ClassCastException.

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