AI-assisted — how our quizzes are made
Primitive and reference types, conversions, operators, control flow, variable inference, strings, arrays, enums, records, and core language semantics.
33 questionsObject construction, fields, methods, initialization order, nested classes, immutability, access control, and lifecycle semantics.
30 questionsInheritance, overriding, overloading, interfaces, abstract classes, dynamic dispatch, sealed hierarchies, pattern matching, and composition.
Lists, sets, maps, queues, iterators, ordering, mutability, concurrent collections, complexity, and collection-selection trade-offs.
37 questionsChecked and unchecked exceptions, propagation, chaining, suppression, try-with-resources, custom exceptions, and failure-handling design.
30 questionsGeneric classes and methods, bounds, wildcards, variance, capture, raw types, heap pollution, bridge methods, and erasure.
32 questionsFunctional interfaces, lambdas, method references, stream pipelines, collectors, reduction, parallel streams, Optional, and side-effect control.
37 questionsObject equality contracts, hash codes, identity, Comparable, Comparator, records, mutable keys, and ordering consistency.
28 questionsThreads, executors, futures, virtual threads, synchronization, locks, atomics, concurrent collections, visibility, ordering, and happens-before.
45 questionsCompilation, bytecode, stack frames, class loaders, linking, initialization, JIT compilation, reflection boundaries, and runtime representation.
33 questionsHeap organization, reachability, references, allocation, garbage collectors, pauses, leaks, finalization, and memory diagnostics.
36 questionsStreams, readers and writers, files, channels, buffers, paths, charsets, sockets, object serialization risks, and resource handling.
42 questionsReflection, method handles, annotations, proxies, service loading, JPMS modules, encapsulation, and runtime metadata.
32 questionsRecords, sealed classes, switch expressions, pattern matching, text blocks, virtual threads, scoped values, and recent language evolution.
32 questionsProfiling, benchmarking, JFR, thread and heap dumps, allocation, contention, exceptions, boxing, caching, and production troubleshooting.
40 questionsWhy can exception-heavy normal control flow hurt performance?
Capturing stack traces and unwinding are comparatively expensive, in addition to clarity problems
Exceptions disable GC
Catch blocks are interpreted only
Throwable objects cannot be optimized
Why should optimization preserve a baseline and repeatable experiment?
To attribute changes and detect regressions under comparable conditions
To make code compile
To disable JIT variance completely
To avoid version control