Java isNull method with Examples

Java isNull() method belongs to the java.util.Objects class as shown below in the diagram. This class was introduced in java7. As the name suggests, the isNull() method is used to check if the object is null or not. In this post, I will be sharing example of isNull() method, difference between Objects.isNull() method and obj == null, and when to use Objects.isNull() method over obj == null.

Read Also: not equal example in Java

1. Syntax:

public static boolean isNull(Object obj)

Returns true if the provided reference is null otherwise returns false.

2. Example:

import java.util.Objects;

public class IsNullExample {
   public static void main(String args[]) {
      String str1 = null;
      String str2 = "JavaHungry";
      
      System.out.println(Objects.isNull(str1)); //true
      System.out.println(Objects.isNull(str2)); //false
   }  
}

Output:
true
false

3. Difference between Objects.isNull() or obj == null

There is no difference between Objects.isNull() and obj == null. Internally, Objects.isNull() method is using obj==null check in the code as shown below:

public static boolean isNull(Object obj)
{
    return obj == null;
}

4. When to use Objects.isNull() method over obj == null

1. Objects.isNull() can be easily used with Java 8 lambda expressions filtering.

For example:

It is much easier, easy to understand and cleaner to write:

.stream().filter(Objects::isNull)

than to write

.stream().filter(i -> i == null)  

In the below code example, we have used the Objects.isNull() method instead of obj == null.

import java.util.List;
import java.util.Objects;
import java.util.stream.*;
import java.util.Arrays;

public class IsNullExampleTwo {
    public static void main(String args[]) {
      List<String> list = Arrays.asList("Alive", "is", null, "Awesome", null);
      List<String>  result = list.stream().filter(Objects::isNull).collect(Collectors.toList());
      System.out.println(result.size());
    }
}

Output:
2

2. You can make a typo as shown below if you are checking whether a boolean variable is null or not.

Boolean bool1 = false;
if(bool1 = null) // Typo, we are using = instead of ==
{
    
}

You can get rid of above typos by using Objects.isNull() method as shown below:

Boolean bool1 = false;
if(Objects.isNull(bool1))
{
    
}

That's all for today, please mention in the comments in case you have any questions related to Java isNull() method with examples.