Given a program (Test.java) that gets two numbers from user input and then carries out a division, revise it to handle exceptional inputs. The given program does those:

Prompt 1

Input 1

Prompt 2

Input 2

Calculation

For the purpose of this project, input 1 should be a double value and input 2 should be a non-zero int value. Upon an invalid input, your program should allow a user to re-enter a piece of data. This would require a loop to validate each input and allow for additional data entry. We need a loop instead of an if-else as you cant assume a second input would be valid.

You will complete this exercise using:

1. Use defensive coding.

Version B: Defensive Coding

You need to use the hasNextXXX methods of Scanner class for the defensive coding version.

public boolean hasNextDouble()

public boolean hasNextInt()

A hasNextXXX method peeks (does NOT read) into user input to decide if the next string to read contains a valid XXX. Use Java API 8 documentation if needed. The following snippet of code illustrates how hasNextXXX may be used:

if (stdIn.hasNextDouble()) { //check before read

dividend = stdIn.nextDouble();

}

else {// no valid input

stdIn.next(); // read string and discard

System.out.println("Invalid dividend");

isValid = false;

}

Follow this pseudo code for defensive coding version:

Do // first num

isValid true

Prompt 1

If has double input

Input 1: nextDouble()

Else

extract input: next()

display err msg

isValid false

End If

While !isValid

Do // second num

isValid true

Prompt 2

If has int input

Input 2: nextInt()

If zero

display err msg

isValid false

End If

Else

extract input: next()

display err msg

isValid false

End If

While !isValid

calculation

This version may work like this:

Enter dividend: 4.2.3

Invalid dividend

Enter dividend: 4/5

Invalid dividend

Enter dividend: 4.5

Enter divisor: 1.5

Invalid divisor

Enter divisor: 0

Input error: divisor can't be zero. Please input again.

Enter divisor: 3

4.5 / 3 = 1.5

/** * Test.java * * If input is of wrong format (InputMismatchException), or * if 0 is provided for divisor, keep asking until valid * data is provided. */

import java.util.Scanner;

public class Test { public static void main(String[] args) { Scanner stdIn = new Scanner(System.in); double dividend; int divisor;

// input System.out.print("Enter dividend: "); dividend = stdIn.nextDouble();

System.out.print("Enter divisor: "); divisor = stdIn.nextInt();

stdIn.close();

// process and result System.out.println(dividend + " / " + divisor + " = " + dividend / divisor); } // end main

} // end Test class