Java Guava | Longs.toArray() method with Examples

The toArray() method of Longs Class in the Guava library is used to convert the long values, passed as the parameter to this method, into a Long Array. These long values are passed as a Collection to this method. This method returns a Long array.

Syntax:

public static long[] toArray(Collection<? extends Number> collection)



Parameters: This method accepts a mandatory parameter collection which is the collection of long values to be converted in to a Long array.

Return Value: This method returns a long array containing the same values as a collection, in the same order.

Exceptions: This method throws NullPointerException if the passed collection or any of its elements is null.

Below programs illustrate the use of toArray() method:

Example 1 :

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java code to show implementation of
// Guava's Longs.toArray() method
  
import com.google.common.primitives.Longs;
import java.util.Arrays;
import java.util.List;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        // Creating a List of Longs
        List<Long> myList
            = Arrays.asList(1L, 2L, 3L, 4L, 5L);
  
        // Using Longs.toArray() method to convert
        // a List or Set of Long to an array of Long
        long[] arr = Longs.toArray(myList);
  
        // Displaying an array containing each
        // value of collection,
        // converted to a long value
        System.out.println(Arrays.toString(arr));
    }
}

chevron_right


Output:

[1, 2, 3, 4, 5]

Example 2 :

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java code to show implementation of
// Guava's Longs.toArray() method
  
import com.google.common.primitives.Longs;
import java.util.Arrays;
import java.util.List;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        try {
            // Creating a List of Longs
            List<Long> myList
                = Arrays.asList(2L, 4L, null);
  
            // Using Longs.toArray() method
            // to convert a List or Set of Long
            // to an array of Long.
            // This should raise "NullPointerException"
            // as the collection contains "null"
            // as an element
            long[] arr = Longs.toArray(myList);
  
            // Displaying an array containing each
            // value of collection,
            // converted to a long value
            System.out.println(Arrays
                                   .toString(arr));
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

chevron_right


Output:

java.lang.NullPointerException

Reference: https://google.github.io/guava/releases/21.0/api/docs/com/google/common/primitives/Longs.html#toArray-java.util.Collection-



My Personal Notes arrow_drop_up

In love with a semicolon because sometimes i miss it so badly)

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.