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));    }} |
[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);        }    }} |
java.lang.NullPointerException
