The hex$2$Dec$($String hexString$)$ method, which comverts a hex string into a decimal number.

Re$-$implement the hex$2$Dec method to throw a NumberformatException if the string is not a

hex string. Catch the exception inside the while loop of main and stay in the program until the

user types $\frac{q}{Q}.$

package exceptions:

inport java.utit$\mathrm{.}5$canner;

public class ToDecinal.

i

public static int bexfodeciaal$($String hex$)$

i

int decinalvalue $=0$;

for $($int $i=0$;$i$ hex. length$()$; i$++)$

$1$

char hexchar $=$ hex.charat$(1)$:

decinalValue $=$ decinalValue $*16+$ hexCharToDecinol$($hexChar$)$:

$\}$

l

return decinalvalue;

public static int hex$($harTobecinallchar ch$)$

f

return $10+ch-{?}^{\text{'}}{A}^{\text{'}}$ :

else $//$ ch is $\text{'}\text{'},\text{'}1\text{'},...,$ or $"9\text{'}$

return $ch-{}^{\text{'}}$;

$\}$

public static void adin$(5$tringlt args$)$

i

Scanner input $=$ new Scanner$($

Systen.in