Open In App
Related Articles

Java Guava | Doubles.toArray() method with Examples

Improve
Improve
Improve
Like Article
Like
Save Article
Save
Share
Report issue
Report
The toArray() method of Doubles Class in the Guava library is used to convert the double values, passed as the parameter to this method, into a Double Array. These double values are passed as a Collection to this method. This method returns a Double array. Syntax:
public static double[] toArray(Collection<? extends Number> collection)
Parameters: This method accepts a mandatory parameter collection which is the collection of double values to be converted in to a Double array. Return Value: This method returns a double 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 :
// Java code to show implementation of
// Guava's Doubles.toArray() method
  
import com.google.common.primitives.Doubles;
import java.util.Arrays;
import java.util.List;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        // Creating a List of Doubles
        List<Double> myList
            = Arrays.asList(1.2, 2.3, 3.4, 4.5, 5.6);
  
        // Using Doubles.toArray() method to convert
        // a List or Set of Double to an array of Double
        double[] arr = Doubles.toArray(myList);
  
        // Displaying an array containing each
        // value of collection,
        // converted to a double value
        System.out.println(Arrays.toString(arr));
    }
}

                    
Output:
[1.2, 2.3, 3.4, 4.5, 5.6]
Example 2 :
// Java code to show implementation of
// Guava's Doubles.toArray() method
  
import com.google.common.primitives.Doubles;
import java.util.Arrays;
import java.util.List;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        try {
            // Creating a List of Doubles
            List<Double> myList
                = Arrays.asList(1.2, 2.3, 3.4, null);
  
            // Using Doubles.toArray() method
            // to convert a List or Set of Double
            // to an array of Double.
            // This should raise "NullPointerException"
            // as the collection contains "null"
            // as an element
            double[] arr = Doubles.toArray(myList);
  
            // Displaying an array containing each
            // value of collection,
            // converted to a double value
            System.out.println(Arrays
                                   .toString(arr));
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

                    
Output:
java.lang.NullPointerException
Reference : https://google.github.io/guava/releases/19.0/api/docs/com/google/common/primitives/Doubles.html#toArray(java.util.Collection)

Last Updated : 31 Jan, 2019
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads
Complete Tutorials