See also Null References - The Billion Dollar Mistake by Tony Hoare, Tony Hoare, Null (SQL), Null reference, Null pointer, Nullable type, Null-Safety

TLDR: A null pointer exception occurs when a program attempts to access or manipulate an object reference that is null, meaning it points to no memory location or object. This issue, prominent in languages like Java, C Sharp, and CPP, often results from failing to initialize variables, dereferencing null pointers, or improper handling of object references.

https://en.wikipedia.org/wiki/Null_pointer

In Java, the NullPointerException is a runtime exception introduced in 1995 with the release of the language. It occurs when methods or properties are invoked on null objects. For instance, calling a method on an uninitialized object reference will trigger this exception. Proper use of null checks (`if (object != null)`) or using modern features like the Optional class and null-safe operators in Java 8 and above can mitigate such issues.

https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html

Null pointer exceptions often lead to application crashes and debugging challenges, especially in large codebases. To prevent this, many languages have introduced features to minimize null usage. Kotlin, introduced in 2011, provides null-safety as a core feature, requiring developers to explicitly handle nullable types, significantly reducing the likelihood of null pointer exceptions.

https://kotlinlang.org/docs/null-safety.html

Effective practices for handling null pointer exceptions include avoiding null values where possible, using default initializations, and employing static analysis tools like FindBugs or SonarQube to identify potential null dereferencing in the codebase. These approaches ensure better application stability and align with secure coding standards.

https://findbugs.sourceforge.net/

Null pointer exception