Quantum Computing – The Next Tech Revolution Technology has evolved rapidly over the last few decades—from bulky mainframe computers to powerful smartphones in our pockets. Yet, despite these advances, traditional computers are approaching their physical limits. This is where quantum computing enters the scene, promising to revolutionize the way we process information and solve complex problems. What Is Quantum Computing? Quantum computing is a new paradigm of computing that uses the principles of quantum mechanics, a branch of physics that explains how matter and energy behave at the smallest scales. Unlike classical computers, which use bits that represent either 0 or 1, quantum computers use qubits. Qubits can exist in multiple states simultaneously, thanks to a property called superposition. Additionally, qubits can be interconnected through entanglement, allowing them to share information instantaneously. These unique properties give quantum computers immense computational power....
Q) What is the difference between abstract class and interface ?
Answer :
1) The abstract keyword is used to declare abstract class.
The interface keyword is used to declare interface.
2) Abstract class have all the features of a normal java class except that we can't instantiate it. We can use abstract keyword to make a class abstract but interfaces are a completely different type and can have only public static final constants and method declarations.
3) Abstract class can have abstract and non abstract methods. Interface can have only abstract methods.
4) Abstract class can have final, non-final, static and non-static variables. Interface has only static and final variables.
5) A java abstract class can have class members like private, protected,etc. Members of a java interface are public by default.
6) Abstract classes can have constructors but interface can't have constructors.
7) A subclass can extend only one abstract class but it can implement multiple interfaces.
8) We can run abstract class if it has main() method whereas we can't run an interface.
Q) What is the use of System class ?
Answer:
The java.lang.System class is one of the core classes. System class comes with many Static methods and using these methods it is possible to take keyboard input, knowing system time, copying an array element into another, to advise to go for garbage collection and to know the system properties etc.
System class is final so that we can't subclass and override it's behaviour through inheritance. System class doesn't provide any public constructors, so we can't instantiate this class and that's why all of it's methods are static.
Fields:
Following are the fields for java.lang.System class
* static PrintStream err - This is the "standard" error output stream.
* static InputStream in - This is the "standard" input stream.
* static PrintStream out - This is the "standard" output stream.
Q) What is instanceof keyword ?
The java instanceof keyword is used to test whether the object is an instance of the specified type.
The instanceof in java is also known as type comparison operator because it compares the instance with type. It returns either true or false. If we apply the instanceof operator with any variable that has null value, it returns false.