Best examples of comparing null pointer exceptions vs. other exceptions in real code

Real-world examples of comparing null pointer exceptions vs. other exceptions

Let’s start with the thing developers actually care about: how these failures show up in real systems. When you look at examples of comparing null pointer exceptions vs. other exceptions in production logs, a few patterns repeat over and over.

In a typical Java microservice, a null pointer exception (NPE) often comes from a missing dependency or misconfigured JSON field:

UserProfile profile = userService.getUserProfile(userId);
String city = profile.getAddress().getCity();  // NPE here if address is null

In the same service, an IndexOutOfBoundsException usually comes from bad assumptions about collection size:

List<Order> orders = orderService.getOrders(userId);
Order latest = orders.get(0);  // IndexOutOfBoundsException if list is empty

Both crash the request, but they signal different problems. NPEs scream “you didn’t account for absence at all.” Index errors say “you knew something existed, but you misjudged how many.” When you gather examples of comparing null pointer exceptions vs. other exceptions across a codebase, you often find that NPEs cluster around data modeling flaws, while other exceptions cluster around boundary conditions or external systems.

Code-level examples of comparing null pointer exceptions vs. other exceptions

To make this less abstract, let’s walk through several code scenarios. These are the best examples I see repeatedly in code reviews and production incident reports.

1. Service integration: Null pointer vs. HTTP / I/O failures

Imagine an order service calling a payment service.

PaymentInfo payment = paymentClient.getPayment(orderId);
// Assume paymentClient returns null when not found

if (payment.isSuccessful()) {       // NPE if payment is null
    ship(orderId);
}

Here, the null pointer exception is entirely local: your code blindly trusts payment to be non-null. Compare that to an IOException or HttpTimeoutException when the remote service is down:

try {
    PaymentInfo payment = paymentClient.getPayment(orderId);
} catch (IOException e) {
    // Network / I/O failure, not a null pointer
}

When teams collect examples of comparing null pointer exceptions vs. other exceptions in their incident postmortems, they usually find:

• NPE: A design or contract problem between services (e.g., returning null instead of a well-defined “not found” object or error code).
• I/O exceptions: Infrastructure or network issues.

The fix strategies differ. NPEs push you toward better null-safety contracts and validation. I/O exceptions push you toward retries, circuit breakers, and better timeouts.

2. API input validation: Null pointer vs. illegal argument

Consider a REST controller receiving JSON input:

public Response createUser(@RequestBody CreateUserRequest request) {
    String emailDomain = request.getEmail().split("@")[1];
    // NPE if request.getEmail() is null
}

A null pointer exception here means you didn’t validate the request body at all. A better approach is to throw an IllegalArgumentException or use a validation framework:

if (request.getEmail() == null || !request.getEmail().contains("@")) {
    throw new IllegalArgumentException("Invalid email");
}

When you build a set of examples of comparing null pointer exceptions vs. other exceptions in API layers, a pattern emerges:

• NPE: The client sent bad or incomplete data, and the server trusted it blindly.
• IllegalArgumentException: The server recognized the bad data and failed fast with a clear message.

From a debugging standpoint, the second behavior is far easier to trace and log, especially when you’re dealing with large distributed systems.

3. Collections and loops: Null pointer vs. index errors

Looping over collections is fertile ground for both NPEs and bounds errors.

List<Product> products = catalogService.getProducts();
for (Product p : products) {
    System.out.println(p.getName().toUpperCase());
    // NPE if p is null
}

Compare that to:

List<Product> products = catalogService.getProducts();
for (int i = 0; i <= products.size(); i++) {
    Product p = products.get(i);  // IndexOutOfBoundsException when i == size()
}

When engineers gather examples of comparing null pointer exceptions vs. other exceptions in collection-heavy code (think analytics, recommendation systems, or ETL jobs), they notice:

• NPEs often indicate partially initialized data or mixed-quality records in the same collection.
• IndexOutOfBoundsException usually points directly to a bad loop condition or an off-by-one bug.

Both are preventable, but they guide you toward different fixes: sanitize data vs. fix loop logic.

4. Type casting: Null pointer vs. class cast

In JVM languages, unsafe casting can trigger either null pointer exceptions or type errors.

Object value = cache.get("user:123");
User user = (User) value;      // ClassCastException if value is not a User
String name = user.getName();  // NPE if value is null

Here, the best examples of comparing null pointer exceptions vs. other exceptions show two distinct failure modes:

• ClassCastException: Your type assumption was wrong.
• NPE: Your existence assumption was wrong.

From a debugging perspective, that distinction matters. A class cast problem often points to a misuse of a shared cache or collection. A null pointer problem points to a missing write or an eviction you didn’t expect.

5. Configuration and environment: Null pointer vs. file / config errors

Configuration loading is another area where these errors diverge.

String dbUrl = System.getenv("DB_URL");
Connection conn = DriverManager.getConnection(dbUrl); // NPE if dbUrl is null

In contrast, if DB_URL is present but malformed, you might see an SQLException instead.

Operations teams who log and analyze examples of comparing null pointer exceptions vs. other exceptions in configuration code often report:

• NPEs show up when environment variables or feature flags are missing in a new environment (staging, a new region, etc.).
• FileNotFoundException or SQLException show up when the configuration exists but points to something unreachable or invalid.

The root causes are different, so your monitoring should be different too. Null-related config errors are often deployment or DevOps pipeline issues, while other exceptions can indicate deeper infrastructure problems.

6. UI and mobile apps: Null pointer vs. lifecycle / state errors

On Android, null pointer exceptions are notorious, especially around the activity and fragment lifecycle.

class ProfileFragment : Fragment() {
    private var user: User? = null

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        nameTextView.text = user!!.name   // NPE if user is still null
    }
}

Compare that with an IllegalStateException from calling a method at the wrong lifecycle phase:

override fun onAttach(context: Context) {
    requireActivity().supportFragmentManager  // IllegalStateException if not attached
}

Mobile teams who catalog examples of comparing null pointer exceptions vs. other exceptions in crash reports (using tools like Firebase Crashlytics or Sentry) usually find:

• NPEs cluster around uninitialized UI state or data that didn’t load in time.
• IllegalStateException clusters around lifecycle misuse and threading issues.

The fixes are different: better nullability annotations and default values vs. better lifecycle awareness and state machines.

2024–2025 trends: Why null pointer exceptions are (slowly) losing ground

There’s some good news. Across JVM and .NET ecosystems, null pointer exceptions are finally getting serious competition from safer patterns.

Recent language and tooling trends include:

• Kotlin and null-safety: Kotlin’s type system forces you to distinguish nullable from non-nullable types, dramatically reducing classic NPEs. The Kotlin team has repeatedly highlighted null-safety as a primary design goal in their official docs (kotlinlang.org).
• Java’s Optional and static analysis: While Optional is far from perfect, it encourages explicit handling of absence. Static analysis tools like SpotBugs and Error Prone catch many NPE risks before they hit production.
• C# nullable reference types: Starting with C# 8, nullable reference types help developers express intent and get compiler warnings when they ignore possible nulls (docs.microsoft.com).

When teams gather new examples of comparing null pointer exceptions vs. other exceptions from 2024–2025 projects, they often see a shift:

• Fewer raw NPEs in newer Kotlin/C# codebases.
• More explicit IllegalArgumentException, IllegalStateException, or domain-specific exceptions where absence is expected and modeled.

In other words, null pointer exceptions aren’t disappearing, but they’re being pushed to the edges—legacy code, interop layers, and poorly typed boundaries.

How to read stack traces when comparing null pointer exceptions vs. other exceptions

Another practical way to use examples of comparing null pointer exceptions vs. other exceptions is to train yourself on stack traces.

A typical NPE trace might show:

java.lang.NullPointerException: Cannot invoke "Address.getCity()" because "address" is null
    at com.example.user.UserService.getUserCity(UserService.java:42)
    at com.example.api.UserController.getCity(UserController.java:27)

Compare that to an IndexOutOfBoundsException trace:

java.lang.IndexOutOfBoundsException: Index 5 out of bounds for length 5
    at java.base/java.util.ArrayList.rangeCheck(ArrayList.java:659)
    at java.base/java.util.ArrayList.get(ArrayList.java:435)
    at com.example.order.OrderService.getOrder(OrderService.java:88)

When you analyze real examples of comparing null pointer exceptions vs. other exceptions in logs, certain heuristics emerge:

• If the trace mentions “because X is null,” you’re usually looking at a missing object or field.
• If the trace mentions “out of bounds” or “illegal state,” you’re dealing with logical constraints being violated.

That mental model speeds up triage. You don’t just see “an exception”; you immediately categorize it as a null problem vs. a boundary or state problem.

Prevention strategies: Using examples to shape coding standards

Once you’ve collected enough internal examples of comparing null pointer exceptions vs. other exceptions, you can turn them into coding standards and linters.

Teams often adopt practices like:

• Prohibiting returning raw null from service boundaries; instead, returning Optional, result wrappers, or domain-specific “empty” objects.
• Requiring explicit IllegalArgumentException or validation errors for public APIs instead of letting NPEs bubble up.
• Enabling strict nullability checks in languages that support them (Kotlin, C#, TypeScript).

These policies are usually backed by internal data: incident reviews, bug trackers, and crash reports. While there isn’t a CDC or NIH for software exceptions, the same principle applies as in health or medicine: you look at patterns in real-world data, then design preventive measures. For a good analogy of data-driven prevention thinking, the CDC’s approach to injury prevention is a useful mental model, even though it’s in a different domain (cdc.gov/injury).

FAQ: Short answers with real examples

Q: Can you give a simple example of a null pointer exception vs. an index exception?
A: Yes. In Java, user.getAddress().getCity() throws a null pointer exception if getAddress() returns null. Meanwhile, list.get(10) throws IndexOutOfBoundsException if the list has fewer than 11 elements. These are classic examples of comparing null pointer exceptions vs. other exceptions in everyday code.

Q: Are null pointer exceptions always the developer’s fault?
A: Mostly, yes. Unlike network or disk failures, null pointer exceptions almost always mean the code failed to account for absence. However, poor third-party library contracts (returning null for everything) can make it much harder to avoid.

Q: What are the best examples of comparing null pointer exceptions vs. other exceptions in microservices?
A: In microservices, NPEs often appear when a downstream response is missing a field you assumed existed, while other exceptions—like HttpTimeoutException or IOException—appear when the downstream service is slow or unavailable. Those paired logs give some of the best examples of comparing null pointer exceptions vs. other exceptions in distributed systems.

Q: How do modern languages help reduce null pointer exceptions?
A: Kotlin’s null-safety, C# nullable reference types, and TypeScript’s strict null checks all force you to express whether something can be null. The compiler then warns you when you ignore that possibility. Official documentation from Microsoft and JetBrains provides detailed guidance and examples (learn.microsoft.com, kotlinlang.org).

Q: Is it better to throw a custom exception instead of letting a null pointer exception occur?
A: Usually, yes. A custom or well-chosen standard exception (like IllegalStateException or IllegalArgumentException) with a clear message is far more helpful than a raw NPE. When teams compile internal examples of comparing null pointer exceptions vs. other exceptions, they consistently find that explicit, intentional exceptions make debugging and on-call work much less painful.