Object-Oriented Programming

An abstract class cannot be instantiated directly, and a static variable has only one copy shared across all instances of a class. The final keyword does not mean a method is implemented elsewhere (that is native), and private restricts access to the defining class only.

public and private are access modifiers controlling class member visibility. transient is a field modifier indicating a variable should not be serialized. 'friendly' is not a Java modifier - the default (package-private) access has no keyword.

Native methods are declared in Java but implemented in platform-specific languages like C or C++. This is done to access low-level hardware features or to optimize performance-critical code.

To solve this question, the user needs to know what the TreeMap class is used for and which collection interface it implements.

The TreeMap class in Java is used to implement a map interface that sorts the keys in natural order. It provides an efficient means of storing key/value pairs in sorted order, making it useful for scenarios where you need to perform operations such as lookups, insertions, and deletions in a sorted collection.

Now, let's go through each option and explain why it is right or wrong:

A. SortedMap: This option is correct. TreeMap implements the SortedMap interface, which extends the Map interface and provides additional methods for retrieving and manipulating elements in a sorted order.

B. Tree: This option is incorrect. While TreeMap is implemented using a tree structure, it does not directly implement the Tree interface.

C. Set: This option is incorrect. TreeMap does not implement the Set interface, which is used for collections of unique elements.

D. SortedSet: This option is incorrect. TreeMap does not implement the SortedSet interface, which is used for sorted collections of unique elements.

The Answer is: A

Every instance of a reference type on the heap has two overhead fields maintained by the CLR: the Object Header (used for synchronization and hashing) and the Method Table Pointer (TypeHandle).

Protected methods in Java are accessible within the same package and to subclasses (even in different packages), and can be overridden by any subclass unless marked final. Option C is correct. Option A is wrong because final methods cannot be abstract. Option B is wrong because private static methods can be called from non-static methods too. Option D is wrong because final methods cannot be overridden.

Static member functions belong to the class rather than individual objects, so they don't have a 'this' pointer. They can only access static members of the class. The 'this' pointer only exists for non-static member functions that operate on specific object instances.

Polymorphism in C++ is achieved through compile-time methods (function overloading, operator overloading) and runtime methods (virtual functions). Virtual base class is used to solve the diamond problem in multiple inheritance but is not itself a type of polymorphism - it's an inheritance-related concept.

Encapsulation is a fundamental object-oriented programming concept that binds together data and the functions that manipulate them into a single unit called a class.

Statement (a) is false - struct members are public by default in C++ (class members are private by default). Statement (b) is true - new and delete operators can be overloaded. Statement (c) is technically incorrect because the subscript operator [] and assignment operator = must be non-static member functions, not friend functions.

Boxing converts value types to reference types by creating an object on the heap and copying the value type value there (Option B and D are correct). Option A is wrong because value types are stored on stack, not heap. Option C is incorrect because unboxing converts reference types back to value types, not value to reference.

In MIDP, the Canvas class is a direct subclass of Displayable, not Screen. Both Canvas and Screen inherit from Displayable at the same level, making the statement false.

Java is fundamentally object-oriented - everything must be part of a class. Even the simplest 'Hello World' program requires a class definition. This is a core design principle of Java, distinguishing it from languages that allow standalone functions or procedures.

Non-static inner classes in Java cannot have static members because they are associated with an instance of the enclosing class. Static members belong to the class itself, not an instance, creating a fundamental conflict. However, static nested classes (declared with 'static' keyword) can have static members. The question is technically correct but should specify 'non-static inner class'.

Static methods are bound at compile-time based on the reference type, not the actual object type. When you have a parent class reference and assign a child object, calling a static method invokes the parent class version, not the child's.