Skip to content
Related Articles
Get the best out of our app
GeeksforGeeks App
Open App
geeksforgeeks
Browser
Continue

Related Articles

AbstractSet add() method in Java with Example

Improve Article
Save Article
Like Article
Improve Article
Save Article
Like Article

The add(E) method of AbstractSet Class appends the specified element to the end of this AbstractSet.

Syntax:

boolean add(E element)

Parameters: This function accepts a single parameter element as shown in the above syntax. The element specified by this parameter is appended to end of the AbstractSet.

Return Value: This method returns True after successful execution, else False.

Exception: This method throws:

  • UnsupportedOperationException: if the add operation is not supported by this collection
  • ClassCastException: if the class of the specified element prevents it from being added to this collection
  • NullPointerException: if the specified element is null and this collection does not permit null elements
  • IllegalArgumentException: if some property of the element prevents it from being added to this collection
  • IllegalStateException: if the element cannot be added at this time due to insertion restrictions

Below program illustrates the working of java.util.AbstractSet.add(E element) method:

Example 1:




// Java code to illustrate boolean add(E element)
import java.util.*;
  
public class AbstractSetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty AbstractSet
        AbstractSet<String> set
            = new TreeSet<String>();
  
        // Use add() method
        // to add elements in the AbstractSet
        set.add("Geeks");
        set.add("for");
        set.add("Geeks");
        set.add("10");
        set.add("20");
  
        // Output the present AbstractSet
        System.out.println("The AbstractSet is: "
                           + set);
  
        // Adding new elements to the end
        set.add("Last");
        set.add("Element");
  
        // Printing the new AbstractSet
        System.out.println("The new AbstractSet is: "
                           + set);
    }
}

Output:

The AbstractSet is: [10, 20, Geeks, for]
The new AbstractSet is: [10, 20, Element, Geeks, Last, for]

Example 2: To demonstrate NullPointerException




// Java code to illustrate
// boolean add(E element)
  
import java.util.*;
  
public class AbstractSetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty AbstractSet
        AbstractSet<Integer> set
            = new TreeSet<Integer>();
  
        // Use add() method
        // to add elements in the AbstractSet
        set.add(10);
        set.add(20);
        set.add(30);
        set.add(40);
        set.add(50);
  
        // Output the present AbstractSet
        System.out.println("The AbstractSet is: "
                           + set);
  
        System.out.println("Trying to add null");
  
        try {
            // Adding null
            set.add(null);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

The AbstractSet is: [10, 20, 30, 40, 50]
Trying to add null
java.lang.NullPointerException

My Personal Notes arrow_drop_up
Last Updated : 24 Dec, 2018
Like Article
Save Article
Similar Reads
Related Tutorials