how to create a TreeSet using collections in java
how to create a TreeSet using collections in java
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In this example we will see how to create a TreeSet.
For creating a TreeSet we have to import the java.util package in which we have the class java.util.TreeSet which contains the definition and various that can be performed on a TreeSet. In this example we have created a class named CollectionExample in which we have created a TreeSet and added some elements to it.
In this example we have used the add(Object obj ) on the object of theTreeSet . The TreeSet object is created by calling the default constructor of the TreeSet using the following statement of the given example,TreeSet<Integer> ts=new TreeSet<Integer>();
The above statement creates a TreeSet having the integer values as elements and constructs a new, empty set, sorted according to the elements' natural
order.
The elements are added using the boolean add(Object obj) on this TreeSet object, which can be done by following statement in the example,
ts.add(4);
This statement add the integer number 4 as an element to the TreeSet.
In this example we have created a class named CollectionExample in which we have created a TreeSet using its default constructor which creates a new empty TreeSet. After that we have added the elements to the TreeSet by invoking the add(Object obj) on the object of the TreeSet.
package r4r.co.in;
import java.util.*;
public class CollectionExample {
/**
* @param args
*/
public static void main(String[] args)
{
// TODO Auto-generated method stub
TreeSet<Integer> ts=new TreeSet<Integer>(); // created a TreeSet object ts
ts.add(2); // adding the elements to the TreeSet object
ts.add(4);
ts.add(7);
ts.add(8);
ts.add(1);
ts.add(9);
System.out.println("The objects of the tree set are as follows: ");
System.out.println(ts); // displaying the contents of the TreeSet
}
}
The output of the above program will be as follows:
The objects of the tree set are as follows:
[1, 2, 4, 7, 8, 9]
As you can see, that the output gives the objects arranged in an ascending order fashion, we can conclude that the by default the objects are placed in ascending order in a TreeSet.
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