java.lang.NullPointerException in Java

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Java.lang.NullPointerException Class

Thrown when an application attempts to use null in a case where an object is required. These include:

Calling the instance method of a null object.
Accessing or modifying the field of a null object.
Taking the length of null as if it were an array.
Accessing or modifying the slots of null as if it were an array.
Throwing null as if it were a Throwable value.

NullPointerException Class Example

public class NullPointerExceptionExample {
    public static void main(String[] args) {
        // Create a string reference but do not initialize it (it is null)
        String myString = null;

        try {
            // Attempt to get the length of the null string
            int length = myString.length(); // This will cause NullPointerException
            System.out.println("Length of the string: " + length);
        } catch (NullPointerException e) {
            // Handle the exception
            System.out.println("Error: Cannot call method on a null reference!");
        } finally {
            System.out.println("Execution completed.");
        }
    }
}

Output:

Error: Cannot call method on a null reference!
Execution completed.