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Concept questionMedium~7 min

Are Spring singleton beans thread-safe?

Separates container instance reuse from concurrency guarantees and designs singleton services around stateless or safely coordinated state.

JavaSpring Boot

Concept questionHard~10 min

How do conditional beans work in Spring Boot?

Uses class, bean, property, resource, and application conditions to provide explicit defaults without ambiguous registration.

JavaSpring Boot

Concept questionHard~10 min

How does Spring Boot auto-configuration work?

Explains imported configuration classes, classpath and bean conditions, ordered defaults, back-off, and the condition report.

JavaSpring Boot

Concept questionHard~10 min

How does Spring Boot decide which configuration value wins?

Explains ordered property sources, profile documents, environment overrides, command-line values, and evidence-driven diagnosis.

JavaSpring Boot

Concept questionEasy~5 min

How do inversion of control and dependency injection work in Spring?

Explains container ownership, dependency declarations, bean creation, and why dependency injection is a specific form of inversion of control.

JavaSpring Boot

Concept questionHard~10 min

How do Spring proxies work, and why can self-invocation bypass advice?

Explains proxy interception, target delegation, JDK versus class proxies, method limits, and the self-invocation boundary.

JavaSpring Boot

Debugging scenarioHard~10 min

How do you diagnose a missing or ambiguous Spring bean?

Traces the injection point, candidate type, registration path, conditions, profiles, generics, qualifiers, and package boundaries.

JavaSpring Boot

Debugging scenarioHard~10 min

How do you handle circular dependencies between Spring beans?

Treats a bean cycle as a design signal, explains constructor failure, and uses delayed resolution only for genuine lifecycle boundaries.

JavaSpring Boot

Architecture scenarioHard~10 min

How do you safely override or exclude Spring Boot auto-configuration?

Uses supported properties, replacement beans, and narrow exclusions in that order, with condition-report and upgrade verification.

JavaSpring Boot

Architecture scenarioHard~10 min

How do you use a prototype or request-scoped bean from a Spring singleton?

Explains why ordinary injection resolves once and chooses providers, factories, scoped proxies, or explicit parameters for shorter-lived dependencies.

JavaSpring Boot

Architecture scenarioMedium~7 min

How do you validate Spring Boot configuration at startup?

Binds related values to typed configuration properties, applies validation constraints, and fails with actionable non-secret diagnostics.

JavaSpring Boot

Architecture scenarioMedium~7 min

How should package structure and component scanning be arranged in Spring Boot?

Places the application class above owned components, uses capability-oriented packages, and keeps scanning and imports deliberate.

JavaSpring Boot

Debugging scenarioHard~10 min

How would you diagnose a Spring Boot application that fails to start?

Preserves the root cause, separates binding, bean, port, classpath, migration, and external failures, and uses Boot's diagnostic reports.

JavaSpring Boot

Comparison questionHard~10 min

What are the trade-offs of lazy initialization in Spring Boot?

Balances faster startup and unused-bean avoidance against delayed failures, first-request latency, memory growth, and readiness semantics.

JavaSpring Boot

Concept questionMedium~7 min

What bean scopes does Spring provide, and when do they matter?

Explains singleton, prototype, request, session, application, and WebSocket scopes as container lifecycle policies.

JavaSpring Boot

Concept questionMedium~7 min

What does the Spring ApplicationContext do?

Explains configuration loading, bean-definition processing, dependency resolution, lifecycle, events, resources, and environment access.

JavaSpring Boot

Concept questionMedium~7 min

What do Spring Boot starters and dependency management provide?

Separates dependency bundles, tested version alignment, transitive dependencies, and runtime auto-configuration.

JavaSpring Boot

Comparison questionEasy~5 min

What is the difference between Spring Framework and Spring Boot?

Separates Spring's application framework and container from Boot's opinionated startup, dependency, configuration, and operational conventions.

JavaSpring Boot

Concept questionMedium~7 min

What is the lifecycle of a Spring bean?

Walks from instantiation and dependency injection through post-processing, initialization callbacks, use, and supported destruction behavior.

JavaSpring Boot

Comparison questionMedium~7 min

When do you use component scanning versus explicit @Bean configuration?

Chooses stereotype scanning for owned application components and explicit factory methods for third-party types, construction policy, and visible composition.

JavaSpring Boot

Comparison questionMedium~7 min

When do you use @ConfigurationProperties instead of @Value?

Uses typed grouped binding and validation for application configuration while reserving @Value for small isolated expressions.

JavaSpring Boot

Comparison questionMedium~7 min

When do you use constructor, field, or setter injection in Spring?

Prefers constructor injection for required dependencies while explaining the limited roles and costs of setter and field injection.

JavaSpring Boot

Comparison questionHard~10 min

When do you use Spring Boot runners, events, and lifecycle hooks?

Chooses hooks by application readiness phase and keeps migrations, warm-up, listeners, and background resources owned and observable.

JavaSpring Boot

Comparison questionMedium~7 min

When do you use Spring profiles versus conditional configuration?

Uses profiles for named environment or deployment groups and focused conditions for feature or capability selection.

JavaSpring Boot