how to iterate over a HashSet using the collection API
how to iterate over a HashSet using the collection API
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In this example we will see how can we iterate over a HashSet using the Iterator interface using collections.
For creating a HashSet we have to import the java.util package in which the HashSet class is defined. In this example we have created a class name CollectionExample in which we created a HashSet and added various elements to it.
In this example we have used the iterator() method defined in the Iterator interface on the object of the HashSet set which iterates over the elements of the set using the next() method defined in the Iterator interface. The following statement demonstrates the same in our example:Iterator<Integer> itr=set.iterator();
This statement invokes the iterator on the HashSet object set.while(itr.hasNext())
{
System.out.println(itr.next());
}
The above loop continues till there are more elements to iterate in the HashSet and also prints the elements returned by the iterator.next().
The output of the above code is the following one :
The number of elements in the set are: 6
The content of the set are: [1, 3, 4, 5, 7, 9]
After iterating over the set the contents of the set are as follows:
1
3
4
5
7
9
package r4r.co.in;
import java.util.*;
public class CollectionExample {
/**
* @param args
*/
public static void main(String[] args)
{
// TODO Auto-generated method stub
HashSet<Integer> set=new HashSet<Integer>(); // creating a HashSet named set
set.add(1); // adding elements to the set
set.add(5);
set.add(3);
set.add(4);
set.add(9);
set.add(7);
set.add(5);
System.out.println("The number of elements in the set are: "+set.size()); // displaying the size of the set
System.out.println("The content of the set are: "+set); // displaying the contents of the set
Iterator<Integer> itr=set.iterator(); // Invoking the iterator over the set
System.out.println("After iterating over the set the contents of the set are as follows: ");
while(itr.hasNext())
{
System.out.println(itr.next()); // displaying the contents of the set
}
}
}
The number of elements in the set are: 6
The content of the set are: [1, 3, 4, 5, 7, 9]
After iterating over the set the contents of the set are as follows:
1
3
4
5
7
9
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