| 1 | What is the role of Span<T> and Memory<T> in .NET, and why can't Span<T> be used inside an async method? C# › Arrays, Span<T> & Memory<T> | C# | Arrays, Span<T> & Memory<T> | Advanced |
| 2 | What is garbage collection in the JVM, and what fundamental problem does it solve compared to manual memory management (like in C/C++)? Java › Garbage Collection | Java | Garbage Collection | Beginner |
| 3 | What is the difference between Error and Exception in Java's Throwable hierarchy, and why should application code generally avoid catching Error subclasses like OutOfMemoryError or StackOverflowError? Java › Exceptions | Java | Exceptions | Intermediate |
| 4 | How does an inner class's implicit reference to its outer instance create a potential memory leak risk, and in what specific scenario does this become a genuine practical concern? Java › Inner Classes & Anonymous Classes | Java | Inner Classes & Anonymous Classes | Intermediate |
| 5 | How does the Java Memory Model's happens-before relationship formally define when changes made by one thread are guaranteed to be visible to another thread, and what role does the volatile keyword play? Java › Concurrency & Threads | Java | Concurrency & Threads | Advanced |
| 6 | How would you implement memory-mapped file I/O using MappedByteBuffer, and what performance advantage does this provide for very large files compared to traditional stream-based reading? Java › I/O & NIO | Java | I/O & NIO | Advanced |
| 7 | What is the role of the ClassLoader in the JVM, and what are the three built-in bootstrap/platform/application class loaders? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Beginner |
| 8 | What does it mean for an object to be 'eligible for garbage collection' in terms of reachability from GC roots? Java › Garbage Collection | Java | Garbage Collection | Beginner |
| 9 | What is the parent delegation model in Java class loading, and why is it important for security and consistency? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Intermediate |
| 10 | What are the phases of class loading (loading, linking, initialization), and what specifically happens during each? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Intermediate |
| 11 | What are the atomic classes in java.util.concurrent.atomic (AtomicInteger, AtomicLong, AtomicReference), and how do they achieve thread-safe operations without traditional locking? Java › Concurrency & Threads | Java | Concurrency & Threads | Intermediate |
| 12 | How does the generational hypothesis (most objects die young) inform the JVM's generational heap structure (young generation, old generation), and how does a minor GC differ from a major/full GC? Java › Garbage Collection | Java | Garbage Collection | Intermediate |
| 13 | What are the four types of references in java.lang.ref (strong, soft, weak, phantom), and how does each affect an object's eligibility for garbage collection? Java › Garbage Collection | Java | Garbage Collection | Intermediate |
| 14 | What is the difference between LocalDate, LocalTime, LocalDateTime, and ZonedDateTime, and when would you use each? Java › Java Date & Time API (java.time) | Java | Java Date & Time API (java.time) | Intermediate |
| 15 | How would you implement a custom ClassLoader to load classes from a non-standard source, such as loading plugin JARs dynamically at runtime, and what challenges arise with class unloading? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Advanced |
| 16 | What is bytecode verification, and what specific categories of invalid or unsafe bytecode does the JVM's verifier reject before allowing a class to run? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Advanced |
| 17 | How does the same class name loaded by two different ClassLoaders create two genuinely distinct types in the JVM, and what problems does this cause (such as with singletons or ClassCastException)? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Advanced |
| 18 | How does Class Data Sharing (CDS) and Application Class Data Sharing (AppCDS) improve JVM startup time, and how does it relate to class loading and verification? Java › Class Loading & Bytecode Verification | Java | Class Loading & Bytecode Verification | Advanced |
| 19 | How do lambda expressions get compiled at the bytecode level using invokedynamic, and how does this differ from how an anonymous inner class implementing the same functional interface would be compiled? Java › Functional Interfaces & Method References | Java | Functional Interfaces & Method References | Advanced |
| 20 | How do the different modern garbage collectors (G1, ZGC, Shenandoah) differ in their approach to minimizing GC pause times, and when would you choose one over the default? Java › Garbage Collection | Java | Garbage Collection | Advanced |
| 21 | What is escape analysis, and how does it enable the JIT compiler to perform stack allocation or scalar replacement for objects that don't actually need heap allocation, reducing GC pressure? Java › Garbage Collection | Java | Garbage Collection | Advanced |
| 22 | How does Metaspace (replacing PermGen since Java 8) store class metadata, and what specific configuration and failure modes differ from the old PermGen model? Java › Garbage Collection | Java | Garbage Collection | Advanced |