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 :
// 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));
}
} |
[1, 2, 3, 4, 5]
Example 2 :
// 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);
}
}
} |
java.lang.NullPointerException