Understanding the Purpose of Guava's checkNotNull Method

What is the purpose of Guava's Preconditions.checkNotNull method in Java?

Preconditions.checkNotNull(myObject);

Guava's `checkNotNull` method is crucial for enforcing non-null contracts in method parameters and variables, providing early error detection and improving code readability.

myObject = Preconditions.checkNotNull(myObject, "myObject must not be null");

Causes

• Improper handling of null references can lead to `NullPointerException` at runtime, which can be hard to debug.
• Codebases often rely on ensuring certain parameters are non-null, especially in public APIs.

Solutions

• Use `Preconditions.checkNotNull()` to enforce non-null parameters and provide clear error messaging when null values are encountered.
• Adopt `checkNotNull` in public methods to validate inputs, making code intention clearer and enhancing overall software reliability.

Mistake: Not including a detail message in the checkNotNull call.

Solution: Always provide a message to clarify what went wrong for better debugging.

Mistake: Using checkNotNull without exception handling.

Solution: Wrap calls in try-catch blocks or ensure calling code can handle the exception gracefully.