1) What is the first step in problem-solving? A) Writing code B) Debugging C) Understanding the problem D) Optimizing the solution Answer: C 2) Which of these is not a step in the problem-solving process? A) Algorithm development B) Problem analysis C) Random guessing D) Testing and debugging Answer: C 3) What is an algorithm? A) A high-level programming language B) A step-by-step procedure to solve a problem C) A flowchart D) A data structure Answer: B 4) Which of these is the simplest data structure for representing a sequence of elements? A) Dictionary B) List C) Set D) Tuple Answer: B 5) What does a flowchart represent? A) Errors in a program B) A graphical representation of an algorithm C) The final solution to a problem D) A set of Python modules Answer: B 6) What is pseudocode? A) Code written in Python B) Fake code written for fun C) An informal high-level description of an algorithm D) A tool for testing code Answer: C 7) Which of the following tools is NOT commonly used in pr...
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.