Null handling
Null handling is the practice of testing whether a value or reference is null or absent before using it and determining how to proceed.
100 Java Mistakes and How to Avoid Them
A null check is a condition that tests whether a reference has the null value.
- How it is used
- Prevents misleading null checks and reduces unexpected NullPointerException failures in ordinary and concurrent Java code.
- How deep it goes
- Explains operator precedence, prevention practices, nullability strategies, and atomic queue handling without developing a complete nullability type system.
- Examples
- Uses faulty string formatting, ArrayList capacity arithmetic, queue polling, ConcurrentMap.merge, and AtomicInteger.updateAndGet examples.
- What you can do after
- Diagnose/debug with precedence-aware inspection, static analyzers, local null checks, and atomic collection methods.
Read how 100 Java Mistakes and How to Avoid Them explains null handling →
The Art of Code
A null check is a conditional test that determines whether a reference or value is absent before it is accessed.
- How it is used
- Improves readable, maintainable navigation through data that may be absent.
- How deep it goes
- Compares nested checks with nullable types, safe navigation, mapping, and fallbacks, but stops short of detailed language semantics.
- Examples
- Uses product pricing and user-address navigation to contrast nested Java checks with Kotlin and Optional-based alternatives.
- What you can do after
- Apply null-safe navigation and explicit fallbacks while keeping business intent visible to callers and maintainers.
Related concepts
- safe-call operatoralternative to · A safe-call operator conditionally accesses or invokes an operation through a nullable receiver, producing null when the receiver is null.
- missing valueused by · A missing value is a marker or condition indicating that an expected data value or reference is absent, unavailable, unknown, or inapplicable.
- NullPointerExceptionaddresses · NullPointerException is a Java runtime exception raised when code improperly dereferences or otherwise uses a null reference where an object is required.
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