Stream ofNullable(T) method in Java with examples

Last Updated : 25 Apr, 2019

The ofNullable(T) method returns a sequential Stream containing a single element if this stream is non-null otherwise method returns an empty Stream. It helps to handle the null stream and NullPointerException. Syntax:

  static <T> Stream<T> ofNullable(T t)

Parameters: This method accepts a single parameter t which is the single element of which the Stream is to be returned. Return value: This method returns a stream with a single element if the specified element is non-null, otherwise an empty stream. Below programs illustrate ofNullable(T) method: Program 1:

Java

// Java program to demonstrate // Stream.ofNullable() method  import java.util.stream.Stream; public class GFG {      public static void main(String[] args)     {          // Create a stream with null         Stream<String> value             = Stream.ofNullable(null);          // Print values         System.out.println("Values of Stream:");         value.forEach(System.out::println);     } }

The output printed on console of IDE is shown below. Output:

Program 2:

Java

// Java program to demonstrate // Stream.ofNullable method  import java.util.ArrayList; import java.util.stream.Stream; public class GFG {      public static void main(String[] args)     {          // Create ArrayList containing names         ArrayList<String> list = new ArrayList<String>();         list.add("Aman");         list.add("Suraj");         list.add("Zufaq");          // create a stream with ArrayList         Stream<ArrayList<String> > value             = Stream.ofNullable(list);          // print values         System.out.println("Values of Stream:");         value.forEach(System.out::println);     } }