Java 8 – Filter null values from a Stream

In this tutorial, we will see how to filter the null values from a Stream in Java.

Example: A stream with null values

In this example, we have a stream with null values. Lets see what happens when we do not filter the null values.

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
public class Example {

   public static void main(String[] args) {

	List<String> list = Arrays.asList("Java", "Stream", null, "Filter", null);
	List<String> result = list.stream().collect(Collectors.toList());
	result.forEach(System.out::println);      
   }

}

Output:

Java
Stream
null
Filter
null

As you can see that the null values are present in the output.

Java 8 Example: Filter null values from a stream

We can use lambda expression str -> str!=null inside stream filter() to filter out null values from a stream.

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
public class Example {

   public static void main(String[] args) {

	List<String> list = Arrays.asList("Java", "Stream", null, "Filter", null);
	List<String> result = list.stream()
			.filter(str -> str!=null)
			.collect(Collectors.toList());
	result.forEach(System.out::println);      

   }

}

Output:

Java
Stream
Filter

Alternatively you can use method reference Objects::nonNull in the filter() method to filter out the null values like this:

List<String> result = list.stream()
		.filter(Objects::nonNull)
		.collect(Collectors.toList());

Java 8 Example 2: Filter null values after map intermediate operation

Similarly we can filter the null values after map operation on a stream.

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
public class Example {

   public static void main(String[] args) {

	List<Integer> list = Arrays.asList(1, 2, 3, null, 4, null, 5);
	List<Integer> result = list.stream()
		.map(num -> num) //here you will be having a different logic
		.filter(n -> n!=null)
		.collect(Collectors.toList());
	result.forEach(System.out::println);      

   }

}

Output:

1
2
3
4
5