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Test your mastery of modern Java features including Virtual Threads, Sealed Classes, Pattern Matching, and JVM internals. Beantworte jede Frage und sieh sofort, ob du richtig liegst — jedes Mal mit Erklärung.
Ein kostenloser Multiple-Choice-Übungstest mit 16 Fragen zu IT. Jede Frage hat eine richtige Antwort und eine kurze Erklärung, und der vollständige Lösungsschlüssel unter dem Quiz dient zugleich als Lernzettel. Kein Konto, kein Zeitlimit — löse ihn so oft du willst.
Dies ist ein kostenloses Multiple-Choice-Quiz mit 16 Fragen. Nach jeder Antwort siehst du, ob sie richtig war — immer mit Erklärung. Keine Anmeldung, kein Zeitlimit: Mach es so oft du willst und nutze den Lösungsschlüssel oben zum Wiederholen, vorher oder nachher.
Richtige Antwort: BThe virtual thread unmounts from its carrier thread, freeing it for other tasks
Project Loom virtual threads unmount from their carrier platform thread upon encountering standard blocking calls, allowing the carrier to execute other runnable virtual threads.
Richtige Antwort: BExecuting blocking file I/O inside a synchronized block or method
When a virtual thread executes inside a synchronized block/method or native call (JNI), it is pinned to its carrier thread and cannot unmount during blocking operations.
Richtige Antwort: AThey must be declared as final, sealed, or non-sealed
Every permitted subclass of a sealed class must explicitly declare a modifier to define its inheritance boundary: final, sealed, or non-sealed.
Richtige Antwort: BRecord patterns
Record patterns allow matching a record type and simultaneously extracting its component variables directly within switch cases and instanceof checks.
Richtige Antwort: BIt offers pure Java bindings to off-heap memory and foreign functions without C glue code
The FFM API allows Java programs to allocate off-heap memory safely via Arena and link foreign native functions without authoring boilerplate C/C++ JNI wrappers.
Richtige Antwort: BIt treats concurrent tasks running in subthreads as a single unit of work with clean cancellation
Structured Concurrency links related concurrent subtasks into a lexical scope, ensuring error propagation, short-circuit cancellation, and reliable cleanup.
Richtige Antwort: CZGC
ZGC performs almost all garbage collection work concurrently, keeping pause times typically under one millisecond regardless of whether the heap is gigabytes or terabytes in size.
Richtige Antwort: AIt must match the accessibility level of the record class itself
A compact constructor in a record implicitly has the same access modifier as the record class itself.
Richtige Antwort: BArena
An Arena controls the lifecycle of native memory segments, providing deterministic, bounded allocation scopes like automatic, global, or confined arenas.
Richtige Antwort: BThe compiler raises a compilation error due to inexhaustive patterns
Pattern matching in switch expressions requires exhaustiveness; omitting a permitted subclass of a sealed hierarchy without a default branch results in a compile-time error.
Richtige Antwort: BScoped values are immutable, bound to a call scope, and shareable efficiently across thousands of threads
Scoped values provide lightweight, immutable data inheritance suited for millions of virtual threads, avoiding the unbound memory overhead of ThreadLocal.
Richtige Antwort: BThe subclass re-opens the inheritance hierarchy so any other class can extend it
The 'non-sealed' modifier breaks the closed hierarchy, allowing unknown subclasses to extend it freely while preserving the sealed rules of its parent.
Richtige Antwort: BTo express vector computations that compile into SIMD instructions on supported hardware
The Vector API allows developers to express data-parallel computations directly in Java, generating optimal Single Instruction Multiple Data (SIMD) CPU instructions at runtime.
Richtige Antwort: BThey combine literal text with embedded expressions processed safely by template processors
String Templates combine text with expressions via processors (like STR or RAW) to safely produce domain objects, JSON, or validated SQL.
Richtige Antwort: BIt reduces the standard object header size from 128/96 bits down to 64 bits
Project Lilliput optimizes object headers by shrinking the mark and class-pointer words into a single 64-bit word, significantly reducing heap footprints.
Richtige Antwort: AIt is scoped only to the lines where the condition evaluates to true
Flow typing governs pattern variables; they are only in scope where the matching condition is definitely true (flow scoping).