| 1 | How do multidimensional arrays work in Java, and how do they differ from truly rectangular arrays in languages like C? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 2 | What utility methods does java.util.Arrays provide for common array operations like sorting, searching, filling, and comparing? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 3 | How do you convert between an array and a List (ArrayList) in both directions, and what pitfalls exist with Arrays.asList()? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 4 | What is array covariance's relationship to generic arrays, and why can't you directly create a generic array like new T[10] or new List<String>[10]? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 5 | How does Java implement covariant array typing, and why is this considered a design flaw that can lead to runtime ArrayStoreException? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Advanced |
| 6 | How would you efficiently copy, resize, or merge large arrays in Java, and what are the performance trade-offs between System.arraycopy(), Arrays.copyOf(), and manual loops? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Advanced |
| 7 | How does the JVM lay out array objects in memory, including the array header overhead, and how does this affect memory efficiency for very large arrays of primitives versus boxed wrapper types? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Advanced |
| 8 | How do you declare, initialize, and access elements of a one-dimensional array in Java? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Beginner |
| 9 | How do you declare and initialize an array of objects (reference types) versus an array of primitives, and what is the key difference in their default values? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Beginner |
| 10 | How does Java handle array bounds checking, and what exception is thrown when accessing an invalid index? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 11 | How do you correctly iterate a 2D array using both traditional indexed for-loops and the enhanced for-each loop, and when is each approach preferable? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 12 | How would you flatten a 2D array into a 1D array, and conversely, reshape a 1D array into a 2D array? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Intermediate |
| 13 | How would you implement an efficient in-place algorithm on a 2D array, such as rotating a matrix 90 degrees, while minimizing extra memory allocation? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Advanced |
| 14 | How would you implement a custom, resizable dynamic array (similar to ArrayList's internal mechanism) from scratch using a raw Java array, including the amortized doubling growth strategy? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Advanced |
| 15 | How would you implement a memory-efficient sparse matrix representation in Java when a large 2D array would mostly contain zero/default values, avoiding the memory waste of a full dense array? Java › Arrays & Multidimensional Arrays | Java | Arrays & Multidimensional Arrays | Advanced |
| 16 | How do you create and work with a multidimensional (rectangular) array versus a jagged array? C# › Arrays, Span<T> & Memory<T> | C# | Arrays, Span<T> & Memory<T> | Beginner |
| 17 | How do generics interact with arrays, and why does the JDK itself sometimes use an unsafe cast (like in ArrayList's internal implementation) to work around the inability to create generic arrays directly? Java › Generics | Java | Generics | Advanced |
| 18 | How does variance (covariance, contravariance, invariance) apply differently to Java arrays versus Java generics, and what practical safety trade-off does this design difference represent? Java › Generics | Java | Generics | Advanced |
| 19 | What are the eight primitive data types in Java, and how do they differ fundamentally from reference types like String or a custom class? Java › Java Fundamentals: Syntax, Data Types & Operators | Java | Java Fundamentals: Syntax, Data Types & Operators | Beginner |
| 20 | What are the key performance differences between ArrayList and LinkedList for common operations (random access, insertion/removal at various positions), and when would you choose one over the other? Java › Collections Framework | Java | Collections Framework | Intermediate |
| 21 | How does Java's integer division and modulo operator behave with negative operands, and how does this differ from the mathematical definition of modulo used in some other contexts (like array indexing wraparound)? Java › Java Fundamentals: Syntax, Data Types & Operators | Java | Java Fundamentals: Syntax, Data Types & Operators | Advanced |