26

Tree Set

Features of JCTreeSet  Constructors and Methods  Examples

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26.1 Features of JCTreeSet

This class adds a convenience constructor to java.util.TreeSet, which provides you with a way of representing an array of Objects as a sorted set. If the elements of the set have a defined ordering principle, it is used by default to construct the tree, or you can provide a Comparator. The ordering must be compatible with the conditions for a java.util.TreeSet. If your array contains duplicate items, JCTreeSet will ensure that only one of them is placed in the sorted set.

JCTreeSet adds this convenience constructor:

• Construct a new JCTreeSet containing the elements in a specified array, sorted according to the elements' natural ordering principle.

JCTreeSet includes the following TreeSet standard constructors:

• Construct an empty TreeSet using a specified Collection, sorted according to the elements' natural ordering principle.
• Construct a new TreeSet containing the elements in the specified Collection, sorted according to the elements' natural ordering principle.
• Construct a new JCTreeSet containing the same elements as the given SortedSet, sorted according to the same ordering.

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26.2 Constructors and Methods

JCTreeSet has constructors that allow you to form a sorted set from the elements of a Collection, an array of Objects, or a SortedSet. A no-parameter constructor lets you instantiate an empty tree set using natural ordering, or you can supply a Comparator to specify how the elements are to be sorted.

JCTreeSet defines no methods of its own. Its methods are inherited from java.util.TreeSet, java.util.AbstractSet, java.util.AbstractCollection, and java.lang.Object.

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26.3 Examples

The example shown here illustrates passing an array of Strings to the constructor. Some Strings are duplicates, but the resulting sorted set contains no duplicates.

import com.klg.jclass.util.JCTreeSet;

public class TreeSetExample {

public static void main(String args[]){
System.out.println("Starting TreeSetExample");
String[] items =
{"moe", "joe", "poe", "zoe", "aoe", "poe", "joe", "moe"};
JCTreeSet ts = new JCTreeSet(items);
System.out.println("The number of items in the array is: " + items.length);
System.out.println("The number of items in JCTreeSet " + ts + " is: " + ts.size());
System.out.println("The last element of " + ts + " is: " + ts.last());
}
}

The output of the program is:

Starting TreeSetExample
The number of items in the array is: 8
The number of items in JCTreeSet [aoe, joe, moe, poe, zoe] is: 5
The last element of [aoe, joe, moe, poe, zoe] is: zoe