# Overview

The **`requireNonNull` method** is a static method of the `Objects` class in Java. It checks whether the input object reference supplied to it is `null`. 

* If the supplied object reference is `null`, then `NullPointerException` is thrown.
* If the object reference is *not* `null`, then the reference is returned as it is.

This method was introduced in Java 8. To use the `requireNonNull` method, import the following module:

```
java.util.Objects
```

# Method signature

```
public static <T> T requireNonNull(T obj)
```

## Parameters
`T obj`: object reference.


## Examples

In the code below, we pass a `null` reference to the method. When the program is run, it throws `NullPointerException`.

import java.util.Objects;

public class Main {
    public static void main(String[] args) {
        Objects.requireNonNull(null);
    }
}


In the following code, we pass a non-null reference to the method. When the program is run, it returns the passed reference.

import java.util.Objects;

public class Main {
    public static void main(String[] args) {
        String s = "hello";
        System.out.println(Objects.requireNonNull(s));
    }
}


What is Objects.requireNonNull in Java?

Ensures an object's non-nullity, else throws NullPointerException; returns the object if not null.