The menu:

$1.$ Enter a fully parenthesized expression.

$2.$ Evaluate a fully parenthesized expression.

$3.$ Convert a fully parenthesized expression to post$-$fix.

$4.$ Evaluate post$-$fix

$5.$ Quit

Enter your choice

public class StackDriver

$\{$

public static void main$($String $[]$args$)$

$\{$

Scanner in $=$ new Scanner$($System$.$in$)$;

String expression $=""$;

boolean quit $=$ false;

while $(!$quit$)\{$

System.out.println$("$Menu:$")$;

System.out.println$("1.$ Enter a fully parenthesized expression."$)$;

System.out.println$("2.$ Evaluate a fully parenthesized expression."$)$;

System.out.println$("3.$ Convert a fully parenthesized expression to post$-$fix."$)$;

System.out.println$("4.$ Evaluate post$-$fix."$)$;

System.out.println$("5.$ Quit"$)$;

System.out.print$("$Enter your choice: $")$;

int choice $=$ in$.$nextInt$()$;

in$.$nextLine$()$;

switch $($choice$)\{$

case $1$:

System.out.print$("$Enter a fully parenthesized expression: $")$;

expression $=$ in$.$nextLine$()$;

if $($isLegal$($expression$))\{$

System.out.println$($expression $+"$ is a legal expression."$)$;

$\}$ else $\{$

System.out.println$($expression $+"$ is not a legal expression."$)$;

$\}$

break;

case $2$:

if $(!$expression.isEmpty$())\{$

evaluateExpr$($expression$)$;

$\}$ else $\{$

System.out.println$("$No expression entered."$)$;

$\}$

break;

case $3$:

if $(!$expression.isEmpty$())\{$

String postFix $=$ convertToPostFix$($expression$)$;

System.out.println$("$Post$-$fix notation: $"+$ postFix$)$;

$\}$ else $\{$

System.out.println$("$No expression entered."$)$;

$\}$

break;

case $4$:

System.out.println$("$Would you like to enter a new post$-$fix expression? $($y$/$n$)")$;

String useExisting $=$ in$.$nextLine$()$;

if $($useExisting$.$equalsIgnoreCase$("$y$"))\{$

System.out.print$("$Enter post$-$fix expression: $")$;

String postFix $=$ in$.$nextLine$()$;

evaluatePostFix$($postFix$)$;

$\}$ else if $(!$expression.isEmpty$())\{$

String postFix $=$ convertToPostFix$($expression$)$;

evaluatePostFix$($postFix$)$;

$\}$ else $\{$

System.out.println$("$No expression available."$)$;

$\}$

break;

case $5$:

quit $=$ true;

System.out.println$("$Exiting program..."$)$;

break;

default:

System.out.println$("$Invalid choice."$)$;$\}$

public static String convertToPostfix$($String str$)\{$

StringBuilder result $=$ new StringBuilder$()$;

ListStack operators $=$ new ListStack$()$;

for $($int i $=0$; i $<$ str$.$length$()$; i$++)\{$

char ch $=$ str$.$charAt$($i$)$;

if $($Character$.$isDigit$($ch$))\{$

result.append$($ch$).$append$(\text{'}\text{'})$;

$\}$ else if $($ch $==\text{'}(\text{'})\{$

operators.push$($ch$)$;

$\}$ else if $($ch $==\text{'})\text{'})\{$

while $(($char$)$ operators.top$()!=\text{'}(\text{'})\{$

result.append$(($char$)$ operators.topAndPop$()).$append$(\text{'}\text{'})$;

$\}$

operators.pop$()$;

$\}$ else if $($ch $==\text{'}+\text{'}||$ ch $==\text{'}-\text{'}||$ ch $==\text{'}*\text{'}||$ ch $==\text{'}/\text{'}||$ ch $==\text{'}\%\text{'})\{$

while $(!$operators.isEmpty$()$ && precedence$($ch$)<=$ precedence$(($char$)$ operators.top$()))\{$

result.append$(($char$)$ operators.topAndPop$()).$append$(\text{'}\text{'})$;

$\}$

operators.push$($ch$)$;

$\}\}$while $(!$operators.isEmpty$())\{$

result.append$(($char$)$ operators.topAndPop$()).$append$(\text{'}\text{'})$;

$\}$return result.toString$().$trim$()$;

$\}$public static void evaluatePostfix$($String postfix$)\{$

ListStack stack $=$ new ListStack$()$;

for $($int i $=0$; i $<$ postfix.length$()$; i$++)\{$

char ch $=$ postfix.charAt$($i$)$;

if $($Character$.$isDigit$($ch$))\{$

stack.push$(($int$)($ch $-\text{'}0\text{'}))$;

$\}$ else if $($ch $==\text{'}+\text{'}||$ ch $==\text{'}-\text{'}||$ ch $==\text{'}*\text{'}||$ ch $==\text{'}/\text{'}||$ ch $==\text{'}\%\text{'})\{$

int op$2=$ stack.topAndPop$()$;

int op$1=$ stack.topAndPop$()$;

switch $($ch$)\{$

case $\text{'}+\text{'}$:

stack.push$($op$1+$ op$2)$;

break;

case $\text{'}-\text{'}$:

stack.push$($op$1-$ op$2)$;

break;

case $\text{'}*\text{'}$:

stack.push$($op$1*$ op$2)$;

break;

case $\text{'}/\text{'}$:

stack.push$($op$1/$ op$2)$;

break;

case $\text{'}\%\text{'}$:

stack.push$($op$1\%$ op$2)$;

break; System.out.println$("$Postfix result: $"+$ stack.topAndPop$())$;