Why treeset in java

C Programming. Control System. Data Mining. Data Warehouse. Javatpoint Services JavaTpoint offers too many high quality services. Java TreeSet class access and retrieval times are quiet fast. Java TreeSet class doesn't allow null element. Java TreeSet class is non synchronized. Java TreeSet class maintains ascending order. TreeSet class declaration Let's see the declaration for java. TreeSet class. It is used to construct an empty tree set that will be sorted in ascending order according to the natural order of the tree set.

It returns the equal or closest greatest element of the specified element from the set, or null there is no such element. If you check TreeMap code you will see that if the comparator wasn't found within the Map object, it will try to cast the key your Employee object directly to Comparator :.

TreeSet is an implementation of SortedSet. You can either let Employee implement the Comparable interface or provide an appropriate Comparator for your TreeSet :. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Ask Question. Asked 8 years, 6 months ago. Active 3 years ago. Viewed 34k times. ClassCastException: Employee cannot be cast to java. Comparable at java. Why does the exception happen and how do I fix it? Improve this question.

Boann Rais Alam Rais Alam 6, 12 12 gold badges 51 51 silver badges 84 84 bronze badges. You need to trust that the error message is correct. Java Training Java Tutorial. Abstract class Interface Abstract vs Interface. Package Access Modifiers Encapsulation. Reinforcement Learning.

R Programming. React Native. Python Design Patterns. Python Pillow. Python Turtle. Verbal Ability. Interview Questions. Company Questions. Artificial Intelligence. Cloud Computing. Data Science. Angular 7. Machine Learning. Data Structures. How do you use TreeSet? Let's see an example of traversing elements in descending order.

What is TreeMap in Java? Java TreeMap class is a red-black tree based implementation. It provides an efficient means of storing key-value pairs in sorted order. It implements the NavigableMap interface and extends AbstractMap class. What is a HashMap used for? This class makes no guarantees as to the order of the map.

It is similar to the Hashtable class except that it is unsynchronized and permits nulls null values and null key. How do I convert TreeSet to array? The method returns an array containing all of the elements in the set. What is a vector in Java? The java. Vector class implements a growable array of objects. Similar to an Array, it contains components that can be accessed using an integer index.