C++ and J2EE Programming Concepts

A J2EE component is a self-contained, reusable software unit that is assembled into a J2EE application. Components like EJBs, servlets, and JSPs have defined interfaces and interact with other components through containers, enabling modular enterprise application development.

Entity beans represent persistent business data that survives system crashes because they are backed by a database. Session beans, in contrast, are transient and only exist for the duration of a client session, representing business processes rather than persistent state.

Session beans are designed for transient, short-lived operations that don't need to survive crashes. They process business logic that can be restarted if lost. Persistence between program invocations requires entity beans or database storage. Database transactions can be initiated from various components, not just session beans.

Separating user data entry (JSP) from business logic (JavaBeans) follows the Model-View-Controller pattern, making applications easier to maintain and update. Changes to the UI (JSP) don't affect business logic (JavaBeans), and vice versa. This is about maintainability, not security, deployment, or visual interest.

XML's tagging structure allows receiving programs to parse and understand data structure without prior knowledge. The tags describe what the data IS, not how to FORMAT or display it (that's XSLT/CSS's job). XML doesn't impose limitations on receivers or add security - its value is in self-describing, structured data exchange.

In J2EE, the EJB container handles all database access (data storage and retrieval) for container-managed persistence (CMP) entity beans. Thin clients, deployment descriptors, and JAR files do not execute database operations or manage bean persistence directly.

Bean-managed persistence means the bean developer writes explicit SQL/JDBC code in the bean's methods to handle database operations. Container-managed persistence (the alternative) lets the container handle storage automatically. The J2EE server shutdown and crash scenarios are unrelated to the persistence mechanism type.

Life cycle methods (ejbCreate, ejbRemove, etc.) are called by the bean's container, not by clients, the server directly, or database calls. The container manages bean instances and invokes these methods at appropriate times during the bean's life cycle. This is fundamental to EJB architecture.

In a multitiered application architecture, the browser runs on the client side and handles user interface presentation. This is known as the presentation tier or first tier. The other tiers (application logic tier and data tier) typically run on servers.

Inline functions are expanded in place by the compiler at compile time rather than being invoked via normal function call overhead at run time. This direct expansion reduces execution overhead, making compile time the correct phase for this mechanism.

In C++, the scope resolution operator :: is used to define member functions outside the class definition, specifying which class the function belongs to.

If no constructor is explicitly declared in a class, the compiler automatically provides a default, no-argument constructor. This ensures that every class always has at least one constructor function available for object instantiation.

Constructors can be overloaded by defining multiple constructors with different parameter lists, allowing objects to be initialized in different ways.

Abstract classes cannot be instantiated directly. They serve as base classes and must be inherited by concrete classes that implement all pure virtual functions.

To solve this question, the user needs to know the concept of access modifiers in object-oriented programming and their default level assigned to the members of a class.

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

A. Public: This option is incorrect. Public access modifier allows members of a class to be accessible from anywhere in the program. However, it is not the default access level assigned to members of a class.

B. Protected: This option is incorrect. Protected access modifier allows the members of a class to be accessible within the class and its subclasses. However, it is not the default access level assigned to members of a class.

C. Private: This option is correct. Private access modifier allows the members of a class to be accessible within the class only. It is the default access level assigned to the members of a class if no other access modifier is explicitly specified.

D. Default: This option is incorrect. Default access modifier allows the members of a class to be accessible within the package only. It is not the default access level assigned to the members of a class.

The Answer is: C

Overloading occurs at compile-time when functions with the same name have different parameters. Overriding happens at runtime when a derived class provides a new implementation for a base class virtual function.

The abort() library function in C and C++ causes abnormal program termination by generating a SIGABRT signal, effectively aborting the program immediately without standard cleanup. Functions like exit() perform normal cleanup before terminating.

A function template in C++ defines a general set of operations that can be applied to various types of data passed as parameters. While a class template defines a family of classes, a function template specifically represents operations (functions). Therefore, 'Both a and c' is incorrect.

Deleting a pointer twice causes undefined behavior, often manifesting as a CPU trap when the memory manager detects the invalid operation. The program may crash or corrupt memory silently.

C++ does not support virtual constructors. Object construction requires knowing the exact type at compile-time. Virtual destructors exist and are important for proper cleanup of derived class objects through base pointers.