Interview
114 bites tagged Interview — interview questions with model answers, and 60-second explainers.
Rust's operator equivalent to Go's if err != nil return err
Tests if you know Rust's ? operator for error propagation. A strong answer names ?, explains it returns Err from the function via Result's Try and FromResidual traits, and unwraps Ok. Red flag: calling it .unwrap() or suggesting manual match is idiomatic.
What is the purpose of the internal directory in Go?
Tests Go visibility boundaries beyond exported vs unexported. A strong answer states that internal is compiler-enforced module privacy, while lowercase is only package-private. Red flag: calling internal a naming convention rather than a build boundary.
Explain 'constraints go down, sizes go up, parent sets position.'
Tests Flutter layout protocol and unbounded width errors. Strong answers trace how a child gets infinite width from a scrolling parent and fix it with a bounded wrapper. Red flag: blaming the child without tracing parent constraints.
Flutter's Widget, Element, and RenderObject trees: roles and relationships
Tests your mental model of Flutter's rendering layers. Strong answer: Widget is immutable configuration; Element is the mutable lifecycle manager owning the RenderObject; RenderObject is the concrete layout and paint entity.
Walk me through a Flutter CI/CD pipeline for Play Store and TestFlight
Tests your ability to orchestrate multi-platform Flutter builds, manage signing secrets, and automate deployments to Google Play Internal Testing and Apple TestFlight.
Explain the purpose of MethodChannel and how it enables Dart-to-native calls
MethodChannel lets Dart encode a method call; the platform host decodes it on the main thread, runs native code, and returns an async result. Your grasp of the async bridge. Calling it synchronous or direct binding.
How does Tween work and how do you use ColorTween with Curves?
This tests value interpolation versus time remapping. A strong answer: Tween maps 0-1 to typed values; ColorTween lerps 2 colors; Curves.easeInOut warps input time before interpolation. Red flag: claiming the curve alters the color output instead of timing.
Explain the core responsibilities of RouterDelegate, RouteInformationParser, and Router in Flutter
Tests Navigator 2.0 architecture split. RouteInformationParser converts URLs to typed config; RouterDelegate owns state and builds the Navigator; Router wires them together and handles engine intents. Red flag: conflating parsing and state or omitting Router.
Explain Flutter's GestureArena and overlapping detector scenario
The arena opens on pointer down; recognizers accept or reject; the last accepted member wins. Your grasp of Flutter gesture disambiguation beyond widgets. Claiming depth or z-order alone decides the winner.
What gesture conflict exists in a scrollable list with horizontal swipes?
Tests Flutter's gesture arena and slop disambiguation. Diagonal motion triggers both vertical scroll and horizontal swipe; the axis whose delta exceeds touch slop first wins the arena. Red flag: claiming Flutter blocks inner gestures or fires both at once.
Explain Flutter's 'constraints down, sizes up' rule and unbounded height error
Parents constrain down, children size up. ListView in Column throws unbounded height as Column gives infinite maxHeight; fix with Expanded or shrinkWrap. Flutter's constraint protocol.
Explain the lifecycle of a State object
List initState through dispose, emphasizing didUpdateWidget reacts to parent config changes. Your grasp of StatefulWidget state transitions and framework hook timing.
What is BuildContext? Give two tree-interaction examples.
Tests if you know BuildContext is an Element handle to a widget's tree location. Strong answers cite Theme.of and Scaffold.of as ancestor lookups, explain the own-context trap, and warn against caching across async gaps. Red flag: calling it the widget itself.
Explain StatelessWidget vs StatefulWidget and when to choose each
This tests immutable UI versus persistent state. StatelessWidget rebuilds when config changes; StatefulWidget owns State surviving rebuilds. Use StatelessWidget for static UI and StatefulWidget for interactive elements.
Explain single-subscription vs broadcast Streams in Dart
Tests dart:async stream lifecycle. Outline: single-subscription allows one listener and emits on listen; broadcast supports many but drops events for late arrivals. Red flag: saying single-subscription allows multiple listeners or buffers events.
What is a Dart closure? Write a function that returns a function.
Tests lexical scoping: define a closure as a function plus its captured environment, show a makeAdder where the inner function uses a parent variable after the parent returns.
What problem does late solve in Dart?
Tests definite assignment and lazy init in null-safe Dart. Strong answers cover: deferred non-nullable field init, lazy final evaluation, and LateInitializationError on early access. Red flag: treating late as nullable or saying it bypasses null safety.
How does a U-shaped EDA pattern influence feature engineering?
Add age squared or splines; trees handle splits but explicit terms aid linear models. U-shapes signal non-monotonicity invisible to linear terms. Log transforms or dropping due to weak correlation.
Describe the difference between ETL and ELT and when to choose each
Tests transform timing and compute location. ETL cleans data before loading via external engines; ELT loads raw data first, then transforms in the warehouse. Pick ETL when pre-load cleansing is needed, ELT when warehouse compute is cheaper.
Why is 99% accuracy misleading with 1% disease prevalence?
Tests class imbalance intuition. A strong answer notes that an all-negative classifier hits 99% accuracy, then names precision, recall, F1, and AUC-PR to expose false negatives and false positives. Red flag: claiming accuracy is fine after rebalancing.
Describe the bias-variance tradeoff and how model complexity affects bias and variance
More complexity cuts bias but boosts variance via overfitting; test error forms a U. Your grasp of error decomposition into bias squared, variance, and noise. Claiming both bias and variance fall as parameters grow.
How do you structure and tokenize animation and transition values?
This tests semantic token architecture for motion. Structure duration and easing into tiered tokens: primitive values, semantic aliases like feedback or navigation, and component bindings. Avoid hardcoding values or using only raw milliseconds without meaning.
How is CSS specificity calculated for a complex selector?
This tests ID-CLASS-TYPE algorithm fluency. A strong answer gives the three-column tally, counts IDs, classes or attributes, and types in order, and notes combinators add zero. A red flag is counting combinators or mixing inline styles into selector scores.
What color wins when an ID and class rule conflict?
Red wins; an ID scores 1-0-0 while a class scores 0-1-0, so the ID rule beats the class rule. Your grasp of CSS specificity scoring beyond source order. Saying the last declared rule wins or that order matters.
Get Interview bites daily.
Five a day, five minutes, offline. With quizzes so it sticks.
Open testing — you’ll join as an early tester.