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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:

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// 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);
    }
}

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

Program 2:

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// 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);
    }
}

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The output printed on console is shown below.
Output:

References: https://docs.oracle.com/javase/10/docs/api/java/util/stream/Stream.html#ofNullable(T)

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