*Creating a new class is simply creating a class with no extensions and no implementations. The signature is as followspublic class MyClass(){}*Extending a class is when you want to use the functionality of another class or classes. The extended class inherits all of the functionality of the previous class. An example of this when you create your own applet class and extend from java.applet.Applet....

instanceof is used to check to see if an object can be cast into a specified type without throwing a cast class exception. isInstance() determines if the specified object is assignment-compatible with the object represented by this Class. This method is the dynamic equivalent of the Java language instanceof operator. The method returns true if the specified Object argument is nonnull and can be cast...

The Serializable interface is just a "marker" interface, with no methods of its own to implement.

Object oriented programming languages directly represent the real life objects. The features of OOPL as inhreitance, polymorphism, encapsulation makes it powerful.

virtual methods are used to use the polymorhism feature in C++. Say class A is inherited from class B. If we declare say fuction f() as virtual in class B and override the same function in class A then at runtime appropriate method of the class will be called depending upon the type of the object.

SELECT Student.name, Student.SIDFROM Student, LevelWHERE Student.SID = Level.SIDAND Level.Level = "freshman"AND Student.Course = 3;

Class ABC{static final float GRAVITATIONAL_CONSTANT = 9.8;public void getConstant(){system.out.println("Gravitational_Constant: " + GRAVITATIONAL_CONSTANT);}}

Multiple inheritance is a feature in C++ by which one class can be of different types. Say class teachingAssistant is inherited from two classes say teacher and Student.

Class C extends A implements B{}

The Object class is the highest-level class in the Java class hierarchy. The Class class is used to represent the classes and interfaces that are loaded by a Java program.

Serialization is the process of writing the state of an object to a byte stream. Deserialization is the process of restoring these objects.

An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object.

The ResourceBundle class is used to store locale-specific resources that can be loaded by a program to tailor the program's appearance to the particular locale in which it is being run.

The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.

Two methods may not have the same name and argument list but different return types.

Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides. The overriding method may not throw any exceptions that may not be thrown by the overridden method.

If a thread attempts to execute a synchronized method or synchronized statement and is unable to acquire an object's lock, it enters the waiting state until the lock becomes available.

A catch clause can catch any exception that may be assigned to the Throwable type. This includes the Error and Exception types.

The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.

With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often causes dirty data and leads to significant errors.