This are my cashier and customer java classes. I need help putting try /catch blocks so the customer cannot spend more money then they have

import java.util.ArrayList;

import java.util.Arrays;

public class Customer {

private String name;

private double cash;

private String[] desiredSandwiches;

private String[] desiredIngredients;

public Customer(String name, double cash, String[] desiredSandwiches, String[] desiredIngredients) {

this.name = name;

this.cash = cash;

this.desiredSandwiches = desiredSandwiches;

this.desiredIngredients = desiredIngredients;

}

/**

* @return the name

*/

public String getName() {

return name;

}

/**

* @param name the name to set

*/

public void setName(String name) {

this.name = name;

}

/**

* @return the cash

*/

public double getCash() {

return cash;

}

/**

* @param cash the cash to set

*/

public void setCash(double cash) {

this.cash = cash;

}

/**

* @return the desiredSandwiches

*/

public String[] getDesiredSandwiches() {

return desiredSandwiches;

}

/**

* @param desiredSandwiches the desiredSandwiches to set

*/

public void setDesiredSandwiches(String[] desiredSandwiches) {

this.desiredSandwiches = desiredSandwiches;

}

/**

* @return the desiredIngredients

*/

public String[] getDesiredIngredients() {

return desiredIngredients;

}

/**

* @param desiredIngredients the desiredIngredients to set

*/

public void setDesiredIngredients(String[] desiredIngredients) {

this.desiredIngredients = desiredIngredients;

}

public void orderSandwich(SandwichMaker sandwichMaker) {

for (String sandwich : desiredSandwiches) {

sandwichMaker.makeSandwich(this, sandwich);

}

}

public boolean chooseIngredient(String ingredient) {

boolean answer = false;

for (String desiredIngredient : desiredIngredients) {

if (desiredIngredient.equalsIgnoreCase(ingredient)) {

answer = true;

}

break;

}

return answer;

}

public boolean givePayment(double total) {

boolean answer = false;

if (cash >= total) {

cash -= total;

answer = true;

}

return answer;

}

@Override

public String toString() {

return "Customer [name=" + name + ", cash=" + cash + ", desiredSandwiches=" + Arrays.toString(desiredSandwiches)

+ ", desiredIngredients=" + Arrays.toString(desiredIngredients) + "]";

}

}

-------------------------------------------------------------

public class Cashier {

private String name;

private Sandwich currentSandwich;

private Customer currentCustomer;

private double cash;

public Cashier(String name, double cash) {

this.name = name;

this.cash = cash;

}

/**

* @return the name

*/

public String getName() {

return name;

}

/**

* @param name the name to set

*/

public void setName(String name) {

this.name = name;

}

/**

* @return the currentSandwich

*/

public Sandwich getCurrentSandwich() {

return currentSandwich;

}

/**

* @param currentSandwich the currentSandwich to set

*/

public void setCurrentSandwich(Sandwich currentSandwich) {

this.currentSandwich = currentSandwich;

}

/**

* @return the currentCustomer

*/

public Customer getCurrentCustomer() {

return currentCustomer;

}

/**

* @param currentCustomer the currentCustomer to set

*/

public void setCurrentCustomer(Customer currentCustomer) {

this.currentCustomer = currentCustomer;

}

/**

* @return the cash

*/

public double getCash() {

return cash;

}

/**

* @param cash the cash to set

*/

public void setCash(double cash) {

this.cash = cash;

}

public void ringUpSandwich(Customer customer, Sandwich sandwich) {

currentSandwich = sandwich;

currentCustomer = customer;

computeTotal();

}

public void computeTotal() {

double total = 0;

for (SandwichType type : SandwichType.values()) {

if (currentSandwich.getType().equalsIgnoreCase(type.getName())) {

total = type.getPrice();

break;

}

}

ArrayList sandwichIngredients = currentSandwich.getIngredients();

for (String sandwichIngredient : sandwichIngredients) {

for (Ingredient ingredient : Ingredient.values()) {

if (ingredient.getName().equalsIgnoreCase(sandwichIngredient)) {

total += ingredient.getPrice();

break;

}

}

}

if (currentCustomer.givePayment(total)) {

cash += total;

}

}

@Override

public String toString() {

return "Cashier [name=" + name + ", currentSandwich=" + currentSandwich + ", currentCustomer=" + currentCustomer

+ ", tillCash=" + cash + "]";

}

}