What is Objects.requireNonNull in Java?

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));
    }
}

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