What is a NullReferenceException, and what are Different methods to solve it?

What is a NullReferenceException, and what are Different methods to solve it?

This dreaded error message happens when you get a NullReferenceException.

This exception is thrown when you try to access a member: for instance, a method or a property on a variable that currently holds a null reference.

What Are References?

We already know that the NullReferenceException is caused by a null reference

In .NET, you can divide data types into two subtypes: value types and reference types.

If you have a variable of a value type, it stores the value itself; however, reference types don’t hold the value itself. They hold a reference that points to where the object lives in memory.

Types such as int, DateTime, and boolean are value types and classes are reference types.

When you try to call a method or another member on the said variable, you got the NullReferenceException.

Understanding the NullReferenceException:

Null reference errors are responsible for a good percentage of all application bugs.

Here are some ways to avoid NullReferenceException:

Null Conditional Operator:

Use the Null Conditional Operator to Avoid NullReferenceExceptions:

One of the best new additions to C# was the null conditional operator. Instead of having a crazy amount of “variable != null” type checks, you can use the “?” and your code will short circuit and return null instead of throwing the exception.

Use Null Coalescing to Avoid NullReferenceExceptions:

?? operator works great for providing a default value for a variable that is null. It works with all nullable data types.

Methods to Prevent Null Reference Exceptions

  1. Initialize variables with valid values.
  2. If a variable can be null, then check for null and handle it appropriately
  3. Use the ? operator on methods when possible. stringvar?.ToUpper();
  4. Use tools like Resharper to help point out potential null reference exceptions

Avoiding NullReferenceException With C# Nullable Types:

What if this decision was enforced by the compiler itself, preventing you and other developers from assigning null.

The compiler is letting me know that “numbers” can be null.

Try/Catch Blocks:

Another step for NullReferenceException is to use a variable that should be initialized in the Inspector. If you forget to do this, then the variable will be null. A different way to deal with NullReferenceException is to use a try/catch block. For example, this code:

In this code example, the variable called myLight is a Light which should be set in the Inspector window. If this variable is not set, then it will default to null.


NullReferenceException happens when your script code tries to use a variable that isn’t set (referencing) and object and the error message that appears in C# tells you a great deal about where in the code the problem happens.NullReferenceException can be avoided by writing code that checks for null before accessing an object or uses try/catch blocks.

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