import java.util.*;			// for Scanner	

/* This program will attempt to input 2 int values and sum them.  An exception is thrown by the JVM if the user does not
 * input the correct type (ints because of s.nextInt()).  The catch block will output the exception and tell the user
 * to try again.  The boolean correct is used to determine whether to repeat the loop or not, in this way we can repeat
 * until the user gets it right!  Note that we must declare the Scanner inside the try block or else, for some reason,
 * the original input values continue to be used and we get into an infinite loop of having the same exception thrown
 * over and over */
 
public class Ch14_2
{
	public static void main(String[] args)
	{
		boolean correct=false;			// repeat until the user gets the input correct
		while(!correct)
		{
			try {
				Scanner s=new Scanner(System.in);
				int x, y,sum=0;
				System.out.println("Enter two integer values one at a time and I will sum them up");
				x=s.nextInt();			// we expect 2 int values, any other type will thrown an InputMismatchException
				y=s.nextInt();
				sum=x+y;				// under normal circumstances, we reach here to compute the sum, output the result
				correct=true;			// and since we got proper input, we set correct to true to exit the while loop
				System.out.println(sum);
			}
			catch(InputMismatchException e)		// if the exception is thrown, transfer control here 
			{									// but notice that the program will then terminate without outputting a sum - see below
				System.out.println(e);
				System.out.println("Your numbers were incorrect, try again");
			}		
		}
	}
}