how to create as subset of a TreeSet using the collections in java
how to create as subset of a TreeSet using the collections in java
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In this example we shall see how to create a subset of 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 subset(startingele, endingele) on the object of the TreeSet ts. The syntax of the subset() method can be shown as,
SortedSet subset(startingele, endingele)
This metod returns the portion of this set whose elements range from startingele, inclusive, to endingele, exclusive.
In this example we have created a TreeSet using the default constructor of the TreeSet class. Then we added the elements to the TreeSet using the add() method on the object of the TreeSet. After creating the TreeSet we have invoked the subset() method on the TreeSet object which gives a set containing the element of the TreeSet within the range of the arguments defined inside the subSet() method. The following example shows how to achieve this functionality,ts.subSet(1, 7);
The above statement creates a set of elements from index 1 to index 7 while element at the index 7 is excluded.
package r4r.co.in;
import java.util.*;
public class CollectionExample {
/**
* @param args
*/
public static void main(String[] args) throws ClassCastException, NullPointerException, IllegalArgumentException
{
// TODO Auto-generated method stub
try
{
TreeSet<Integer> ts=new TreeSet<Integer>(); // creating a TreeSet
ts.add(new Integer(2)); // adding the Integer objects to the TreeSet
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 objects contained in the TreeSet
System.out.println(ts.subSet(1, 7)); // displaying contents of the subset between the elements 1 to 7 excluding 7
System.out.println(ts.subSet(1, true, 7, true)); // displaying the contents of the subset between the elements 1 to 7 including 1 and 7
}
catch(ClassCastException e) // handling ClassCastException if casting is not done properly
{
System.out.println(e.getMessage());
}
catch(NullPointerException e) // handling the NullPointerException if Null value is passed as argument in subSet() method
{
System.out.println(e.getLocalizedMessage());
}
catch(IllegalArgumentException e) // handling the IllegalArgumentException thrown if illegal arguments are passed in subSet() method
{
System.out.println(e.getMessage());
}
}
}
The output of the above written code is as follows:
The objects of the tree set are as follows:
[1, 2, 4, 7, 8, 9]
The subset excluding the second argumnet is: [1, 2, 4]
The subset of TreeSet including the first and second argument is: [1, 2, 4, 7]
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