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
