java util TreeSet Class - java.util.TreeSet Class in Java
TreeSet Class in Java
The TreeSet class works exactly the same as the HashSet class with one notable exception: instead of keeping its elements unordered, a TreeSet keeps its elements ordered internally. Not only all the elements ordered, but the tree is balanced. More specifically, it's a red−black tree. Having a balanced tree guarantees a quick o(log n) search time at the cost of a more time−intensive insertion (and deletion). Of course, elements added to the tree must be orderable.
A NavigableSet implementation based on a TreeMap. The elements are ordered using their natural ordering, or by a Comparator provided at set creation time, depending on which constructor is used.
Because TreeSet implements the SortedSet interface as well as the Set interface, understanding TreeSet is a little more involved than HashSet.
How TreeSet Works Internally in Java ?
Java TreeSet class is part of Java’s collections framework. It implements the NavigableSet interface, which in turn extends the SortedSet interface.
The TreeSet class internally uses a TreeMap to store elements. The elements in a TreeSet are sorted according to their natural ordering. You may also provide a custom Comparator to the TreeSet at the time of creation to let it sort the elements based on the supplied comparator.
TreeSet keeps its elements ordered internally. Not only all the elements ordered, but the tree is balanced.
How TreeSet Sort Elements Internally in Java ?
TreeSet keeps its elements sort (ordered) internally. Not only all the elements sort (ordered), but the tree is balanced.
In order to maintain an ordering, elements added to a tree set must provide some way for the tree to order them. If the elements implement the Comparable interface, the first constructor is sufficient. If, however, the objects aren't comparable or you don't like the default ordering provided, you can pass along a custom Comparator to the constructor that will be used to keep elements ordered. Once the TreeSet is created, you cannot change the comparator.
What are the Red Black Tree Rules in Java ?
- Every node in the tree is either black or red.
- The root is always black.
- If a node is red, its children must be black.
- Every path from the root to a leaf (or null child) must contain the same number of black nodes.
This Java TreeSet tutorial also helpful for the following questions :
- What is a TreeSet ?
- How TreeSet works in java ?
- Internal implementation of TreeSet in java ?
- Java TreeSet complete reference ?
In this tutorial you can learn about java.util.TreeSet class and its examples. And also learn how to use java.util.TreeSet class.
java.util.TreeSet class Example
The following example shows how to use TreeSet with Iterator.
How to use TreeSet with Iterator
The following example shows how to use TreeSet with Arrays, Set and Iterator in descending order.
How to use TreeSet with Arrays
java.util.TreeSet class Example 4
The following example shows how to compare two Set Collections.
how to compare two Set Collections
The following example shows how to save Set Collection into file.
How to save Set Collection into file
The following example shows how to retrieve Set Collection from file.
How to retrieve Set Collection from file
The following example shows how to create a tree with a Comparator, filling the tree, and getting that comparator.
How to create a tree with a Comparator