how to iterate over a TreeSet using Iterator in collections in java
how to iterate over a TreeSet using Iterator in collections in java
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In this example we will see how to iterate over a TreeSet using the Iterator interface in a collection.
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 iterator() method of the Iterator interface on the object of the TreeSet class. This iterator() method is responsible for iterating down the elements of the TreeSet object. The elements are iterated by using the next() method on the Iterator object.
In this example we have created a class named CollectionExample in which we have created a TreeSet. Then we have added the elements to the TreeSet using the add(Object obj) method on the TreeSet object ts. After that, we have invoked the iterator() method on the TreeSet object i.e ts which is shown as,Iterator<Integer> itr= ts.iterator();
Then finally we have iterated over the the Iterator object itr by using the hasNext() method, and print the values returned by the next() method invoked on the iterator object. The same is done by these statements in the following example,
while(itr.hasNext()){
System.out.println(itr.next());
}
ackage r4r.co.in;
import java.util.*;
public class CollectionExample {
/**
* @param args
*/
public static void main(String[] args)
{
// TODO Auto-generated method stub
// in the below TreeSet Constructor we are passing the comparator object, by creating an anonymous class
TreeSet<Integer> ts=new TreeSet<Integer>();
ts.add(2);
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);
Iterator<Integer> itr= ts.iterator(); // Invoking the iterator on the object of the TreeSet
System.out.println("The contents of the TreeSet using Iterator is as displayed: ");
while(itr.hasNext())
{
System.out.println(itr.next()); // displaying the objects of the TreeSet using the iterator
}
}
}
The output of the program is shown as following:
The objects of the tree set are as follows:
[1, 2, 4, 7, 8, 9]
The contents of the TreeSet using Iterator is as displayed:
1
2
4
7
8
9
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