Why do we get null pointer exception in Java?

1. Why NullPointerException occur in the code NullPointerException is a situation in code where you try to access/ modify an object which has not been initialized yet. It essentially means that object reference variable is not pointing anywhere and refers to nothing or ‘ null ‘. A example java program which throws null pointer exception. 2.

When to throw an object of NullPointerException?

The object of NullPointerException class thrown when an application attempts to use null in a case where an object is required. 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.

How to assign a null value to an object in Java?

In Java, a special null value can be assigned to an object reference. NullPointerException is thrown when program attempts to use an object reference that has the null value. Invoking a method from a null object. Accessing or modifying a null object’s field. Taking the length of null, as if it were an array.

Which is an example of an application of null?

One application of null is in implementing data structures like linked list and tree. Other applications include Null Object pattern (See this for details) and Singleton pattern. The Singleton pattern ensures that only one instance of a class is created and also, aims for providing a global point of access to the object.

Why is resultset.next throwing a null pointer exception?

I’ve used essentially the same code further up to cycle over a resultset and it worked fine and I’ve run the SQL directly and that returns the correct results so I’m confused as to why the resultSet.next () could be throwing a null pointer exception?

What causes the NullPointerException to be thrown?

NullPointerException is thrown when program attempts to use an object reference that has the null value. These can be: Invoking a method from a null object. Accessing or modifying a null object’s field. Taking the length of null, as if it were an array. Accessing or modifying the slots of null object, as if it were an array.

Is the NullPointerException a checked or Unchecked exception?

Answer: NullPointerException is not a checked exception. It is a descendant of RuntimeException and is unchecked. #3) How do I stop NullPointerException? Answer: Some of the best practices to avoid NullPointerException are: Use equals () and equalsIgnoreCase () method with String literal instead of using it on the unknown object that can be null.