18-02-25
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Q)What is the hierarchy of exception classes?
  =>java.lang.Throwable is the super class of all exception classes in Java.
  =>It has 2 sub classes.
             1)java.lang.Exception
	     2.)java.lang.Error
  =>java.lang.Error class representing exceptions can't be handled by application developers.They  are related to JVM issues.

=>It means in Java application, we can handle those exceptions which are sub classes
of only java.lang.Exception.

=>java.lang.Exception class has many sub classes. These sub classes can be divided
into two areas.
                   1)unchecked exception classes
		   2)checked exception classes
=>java.lang.RuntimeException and its sub classes represent unchecked exceptions.
=>Every other sub class of java.lang.Exception is of type checked.

Q)How many "catch" blocks can be associated with one try block?
=>Any many. 
=>It depends upon the number of different exceptions that may be
raised in try block.
=>Whenever we are writing multiple catch blocks for a try block, ensure that super class
exception type should come last. Otherwise, Java compiler causes compilation errors
as unreachable code is a syntactical error in Java.

Q)Example program on multiple catch blocks for one try block.
import java.util.Scanner;
class MultiCatchExample{
	public static void main(String[] args) {
		int quotient=1;//identity of division
		System.out.println("Program started");
		Scanner scanner=new Scanner(System.in);
		try
		{
		    System.out.print("Enter the numerator:");
		    int n=scanner.nextInt();
                    System.out.print("Enter the denominator:");
		    int d=scanner.nextInt();
		    quotient=n/d;
		    System.out.println("Quotient is "+quotient);
		}		
		catch (ArithmeticException e)
		{
			System.out.println(e.getMessage());
		}		
		catch(java.util.InputMismatchException e)
		{
			System.out.println("Please enter integral numbers only");
			e.printStackTrace();
		}
		catch(Exception e)
		{
			System.out.println("Something went wrong");
		}
		System.out.println("Program ended successfully");
	}
}
Q)What is an unchecked exception?
=>For which type of exceptions, Java compiler doesn't force to implement 
exception handling, they are known as unchecked exceptions.

Q)What is an checked exception?
=>For which type of exceptions, Java compiler  forces to implement 
exception handling, they are known as checked exceptions.
=>For which type of exceptions, non-handling is a syntactical error
reported by the compiler, those exceptions are known as checked
exceptions.