Table of Contents

NullPointerException

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.

https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it

NullPointerExceptions are exceptions that occur when you try to use a reference that points to no location in memory (null) as though it were referencing an object. Calling a method on a null reference or trying to access a field of a null reference will trigger a NullPointerException.

  public class Example {
    public static void main(String[] args) {
	Object obj = null;
	obj.hashCode();
    }
}

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2022-10-28 Fri 22:39