Develop Reference

Why won't my bubble sort sort my array of objects?

I've created a program with an object called CarlysCatering. I'm trying to sort the CarlysCatering objects by number of guests.
I've tried using a bubble sort but I get an error message.
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
CarlysCatering[] event = new CarlysCatering[100];
event[0] = new CarlysCatering(10, "A547", "6874714145", 0);
event[1] = new CarlysCatering(100, "B527", "6874874945", 2);
event[2] = new CarlysCatering(50, "C546", "6874785145", 3);
event[3] = new CarlysCatering(40, "L577", "6874321485", 1);
event[4] = new CarlysCatering(70, "A111", "6874714145", 4);
event[5] = new CarlysCatering(90, "K222", "6874974855", 2);
event[6] = new CarlysCatering(11, "F798", "6875555555", 3);
event[7] = new CarlysCatering(17, "T696", "6474763898", 0);
//SORT
int selection = 0;
do {
System.out.println("1 - sort by eventID. 2 - sort by number of guests. 3 - sort by event type. 4 - quit");
selection = input.nextInt();
input.nextLine();
if(selection == 1) {
}
if(selection == 2) {
int n = event.length;
for (int i = 0; i < n - 1; i++) {
for (int j = 0; j < n - i - 1; j++) {
if (event[j].getGuests() > event[j + 1].getGuests()) {
// swap arr[j+1] and arr[i]
CarlysCatering temp = event[j];
event[j] = event[j + 1];
event[j + 1] = temp;
}
}
}
}
} while (selection != 4);
//Print totals
event[0].getTotals(); event[1].getTotals(); event[2].getTotals(); event[3].getTotals(); event[4].getTotals(); event[5].getTotals(); event[6].getTotals(); event[7].getTotals();
}
////////////////////////////////////////////////////// STATIC METHODS //////////////////////////////////////////////////////////////////////
}
public class CarlysCatering {
public static final int PRICE_PER_GUEST_HIGH = 35;
public static final int PRICE_PER_GUEST_LOW = 32;
public static final int CUTOFF_VALUE_LARGE = 49;
private int guests;
private int totalPrice;
private String eventID;
private String phoneNumber;
private String eventType;
private boolean largeEvent;
///////////////////////////////////////////////////// CONSTRUCTORS //////////////////////////////////////////////////////////////////
CarlysCatering() {
this.guests = 0;
this.eventID = "A000";
this.phoneNumber = "0000000000";
}
CarlysCatering(int guests, String eventID, String phoneNumber, int eventType) {
this.guests = guests;
this.eventID = eventID;
//Phone Number formatting
String phoneNumber2 = "";
int count = 0;
for(int i = 0; i < phoneNumber.length(); i++) {
if (Character.isDigit(phoneNumber.charAt(i))) {
phoneNumber2 += phoneNumber.charAt(i);
count += 1;
}
}
if (count != 10) {
this.phoneNumber = "0000000000";
} else {
String phoneNumber3 = "(" + phoneNumber2.substring(0,3) + ") " + phoneNumber2.substring(3,6) + "-" + phoneNumber2.substring(6,10);
this.phoneNumber = phoneNumber3;
}
//Event type formatting
final String[] eventString = new String[5];
eventString[0] = "wedding"; eventString[1] = "baptism"; eventString[2] = "birthday"; eventString[3] = "corporate"; eventString[4] = "other";
if(eventType > -1 && eventType < 5) {
this.eventType = eventString[eventType];
} else {
this.eventType = eventString[4];
}
}
///////////////////////////////////////////////////////// SETTERS AND GETTERS /////////////////////////////////////////////////
//Setters
public void setEventID(String eventID) {
this.eventID = eventID;
}
public void setGuests(int guests) {
this.guests = guests;
}
public void setPhoneNumber(String phoneNumber) {
String phoneNumber2 = "";
int count = 0;
for (int i = 0; i < phoneNumber.length(); i++) {
if (Character.isDigit(phoneNumber.charAt(i))) {
phoneNumber2 += phoneNumber.charAt(i);
count += 1;
}
}
if (count != 10) {
this.phoneNumber = "0000000000";
} else {
String phoneNumber3 = "(" + phoneNumber2.substring(0, 3) + ") " + phoneNumber2.substring(3, 6) + "-" + phoneNumber2.substring(6, 10);
this.phoneNumber = phoneNumber3;
}
}
public void setEventType(String eventType) {
this.eventType = eventType;
}
//Getters
public int getTotalPrice() {
return totalPrice;
}
public int getGuests() {
return guests;
}
public String getEventID() {
return eventID;
}
public String getPhoneNumber() {
return phoneNumber;
}
public String getEventType() {
return eventType;
}
/////////////////////////////////////////////////////// ADDITIONAL METHODS ///////////////////////////////////////////////////////////////////
public void isLargeEvent() {
if (this.guests > CUTOFF_VALUE_LARGE) {
largeEvent = true;
System.out.println("Yes this is a large event.");
} else {
largeEvent = false;
System.out.println("This is not a large event");
}
}
public void getTotals() {
boolean largeEvent = false;
if(this.guests > CUTOFF_VALUE_LARGE) {
largeEvent = true;
this.totalPrice = this.guests * PRICE_PER_GUEST_HIGH;
} else {
largeEvent = false;
this.totalPrice = this.guests * PRICE_PER_GUEST_LOW;
}
System.out.println("The number of guests attending event " + this.eventID + " " + this.eventType + " is: " + this.guests + ". The total price is $" + this.totalPrice);
System.out.println("Large event: " + largeEvent);
System.out.println("The phone number on file is " + this.phoneNumber);
}
// Static methods
public static void showMotto() {
System.out.println("*****Carly's makes the food that makes it a party.*****");
}
}
The error message I get when I try to sort by guests is Exception in thread "main" java.lang.NullPointerException and then error code exit -1. The line that's causing the error is:
if (event[j].getGuests() > event[j + 1].getGuests()) {

You create an Array with the size 100.
After that, you fill it from index 0 to 7.
Every other place of the array remains null but the length is 100.
Then, you try to sort the array.
This throws a NullPointerException when you try to dereference (access) the 8. element:
event[j+1].getGuests()
I think you should use a smaller array(size 8) or a List.

Java values of toString() not printing

I am new to Java programming. I developed a Pizza class that takes for parameters and outputs the description and cost. I developed a PizzaOrderArray class that stores the pizza orders in an array. I have a class containing the main method also.
When I tried to print the values of the orders, nothing prints yet debugging shows that the proper methods and loops were entered.
What am I doing incorrect? I have invested many hours and am still very confused. Any suggestions, please? Thank you! I appreciate it.
Pizza.java
import java.text.NumberFormat;
import java.util.Locale;
public class Pizza {
public Pizza(String size, int numCheeseTop, int numPepTop, int numHamTop) {
if (!setPizzaSize(size)) {
System.out.println(size + " is invalid size." + "Use small, medium or large.");
}
setNumCheese(numCheeseTop);
setNumPep(numPepTop);
setNumHam(numHamTop);
}
public Pizza(String size, int numPepTop, int numHamTop) {
if (!setPizzaSize(size)) {
System.out.println(size + " is invalid size." + "Use small, medium or large.");
}
pizza_cheese = 0;
setNumPep(numPepTop);
setNumHam(numHamTop);
}
public Pizza(String size, int numHamTop) {
if (!setPizzaSize(size)) {
System.out.println(size + " is invalid size." + "Use small, medium or large.");
}
pizza_pep = 0;
setNumHam(numHamTop);
pizza_cheese = 0;
}
public Pizza(String size) {
if (!setPizzaSize(size)) {
System.out.println(size + " is invalid size." + "Use small, medium or large.");
}
pizza_cheese = 0;
pizza_pep = 0;
pizza_ham = 0;
}
public Pizza() {
pizza_size = "small";
pizza_cheese = 0;
pizza_pep = 0;
pizza_ham = 0;
}
public Pizza(Pizza copyPizza) {
pizza_size = copyPizza.getPizzaSize();
pizza_cheese = copyPizza.getNumCheese();
pizza_pep = copyPizza.getNumPep();
pizza_ham = copyPizza.getNumHam();
}
//Setters
public boolean setPizzaSize(String size) {
if (size.equalsIgnoreCase("small") || (size.equalsIgnoreCase("medium") || (size.equalsIgnoreCase("large")))) {
pizza_size = size.toLowerCase();
return true;
}
return false;
}
public void setNumCheese(int numCheeseTop) {
pizza_cheese = numCheeseTop;
}
public void setNumPep(int numPepTop) {
pizza_pep = numPepTop;
}
public void setNumHam(int numHamTop) {
pizza_ham = numHamTop;
}
//End of setters
//Getters
public String getPizzaSize() {
return pizza_size;
}
public int getNumCheese() {
return pizza_cheese;
}
public int getNumPep() {
return pizza_pep;
}
public int getNumHam() {
return pizza_ham;
}
//End of getters
public double calcCost() {
if (pizza_size.toLowerCase() == "small") {
return 10 + ((pizza_cheese + pizza_pep + pizza_ham) * 2);
}
if (pizza_size.toLowerCase() == "medium") {
return 12 + ((pizza_cheese + pizza_pep + pizza_ham) * 2);
}
if (pizza_size.toLowerCase() == "large") {
return 14 + ((pizza_cheese + pizza_pep + pizza_ham) * 2);
}
if (pizza_size.toLowerCase() != "small" && pizza_size.toLowerCase() != "medium"
&& pizza_size.toLowerCase() != "large") {
System.out.println("Invalid pizza size");
return 0;
}
return 0;
}
public String getDescription() {
return pizza_size + " pizza with " + pizza_cheese + " cheese toppings " + pizza_pep + " pepperoni toppings and "
+ pizza_ham + " ham toppings "; //+ " which is " + money.format(pizza2.calcCost());
}
//private String pizza_size;
//private int pizza_cheese, pizza_pep, pizza_ham;
public String pizza_size;
public int pizza_cheese, pizza_pep, pizza_ham;
} //End of Pizza class
PizzaOrderArray.java
import static java.lang.System.out;
public class PizzaOrderArray {
public String pizza_size;
public int pizza_cheese, pizza_pep, pizza_ham;
//private String pizza_size;
//private int pizza_cheese; pizza_pep; pizza_ham;
private Pizza[] pizza;
private int index = 0;
public PizzaOrderArray() {
System.out.println("PizzaOrderArray()");
index = 1;
pizza = new Pizza[index];
}
public PizzaOrderArray(int i) {
System.out.println("PizzaOrderArray(int i)");
index = 1;
pizza = new Pizza[index];
}
public PizzaOrderArray(PizzaOrderArray poa) {
System.out.println("PizzaOrderArray(PizzaOrderArray poa)");
pizza = new Pizza[poa.index];
index = poa.index;
for (int i = 0; i < poa.index; i++) {
System.out.println("PizzaOrderArray(PizzaOrderArray poa) for loop");
pizza[i] = new Pizza(poa.pizza[i]);
}
}
public void setPizza(int index1, Pizza newpizza) {
System.out.println("Inside of setPizza");
pizza[index1] = new Pizza(newpizza);
}
public String getPizzaSize() {
System.out.println("Inside of getPizzaSize");
return pizza_size;
}
public int getNumCheese() {
System.out.println("Inside of getNumCheese");
return pizza_cheese;
}
public int getNumPep() {
System.out.println("Inside of getNumPep");
return pizza_pep;
}
public int getNumHam() {
System.out.println("Inside of getNumHam");
return pizza_ham;
}
public String toString() {
String s = "";
int indexUsed = 0;
System.out.println("Inside of toString");
for (int i = 0; i < indexUsed; i++) {
s = (s + pizza[i].toString());
}
System.out.println("Inside of toString for loop");
return s;
}
public double calcTotal() {
double r = 0.0;
System.out.println("Inside of calcTotal");
for (int i = 0; i < index; i++) {
System.out.println("Inside of calcTotal for loop");
r = r + pizza[i].calcCost();
}
return r;
}
public boolean equals(PizzaOrderArray orderarray) {
boolean r = false;
System.out.println("Inside of equals");
if (orderarray.pizza.length != pizza.length) {
System.out.println("Inside of equals if");
return r;
}
for (int i = 0; i < orderarray.pizza.length; i++) {
if (pizza[i].equals(orderarray.pizza[i])) {
System.out.println("Inside of equals for-if");
r = true;
} else {
System.out.println("Inside of equals for-else");
return false;
}
}
System.out.println("Return of equals");
return r;
}
} //End of PizzaOrderArray class
V4_Project_15_page_418.java
import java.text.DecimalFormat;
import java.util.Scanner;
import java.util.Arrays;
public class V4_Project_15_page_418 {
public static void main(String args[]) {
//Order1
PizzaOrderArray order1 = new PizzaOrderArray();
Pizza pizzaone = new Pizza("Medium", 0, 0, 0);
Pizza pizzatwo = new Pizza("Small", 1, 0, 0);
order1.setPizza(0, pizzaone);
System.out.println("Order 1: ");
System.out.println(order1.toString());
System.out.println(order1);
System.out.println();
//Order2
Pizza pizzathree = new Pizza(pizzatwo);
PizzaOrderArray order2 = new PizzaOrderArray(2);
order2.setPizza(0, pizzaone);
order2.setPizza(0, pizzatwo);
System.out.println("Order 2: ");
System.out.println(order2.toString());
System.out.println(order2);
System.out.println();
//Order3
PizzaOrderArray order3 = new PizzaOrderArray(1);
order3.setPizza(0, pizzaone);
order3.setPizza(0, pizzatwo);
System.out.println("Order 3: ");
System.out.println(order3.toString());
System.out.println(order3);
System.out.println();
//Order4
PizzaOrderArray order4 = new PizzaOrderArray(order3);
System.out.println("Order 4: ");
System.out.println(order4.toString());
System.out.println(order4);
//TEST THE PROGRAM
System.out.println("TEST: The total for order 4 is: " + order4.calcTotal());
System.out.println();
//Order5
PizzaOrderArray order5 = new PizzaOrderArray(order1);
System.out.println("Order5: ");
System.out.println(order5);
System.out.println();
}//End of main class
}//End of V4_Project_15_page_418 class
Output:
PizzaOrderArray()
Inside of setPizza
Order 1:
Inside of toString
Inside of toString for loop
Inside of toString
Inside of toString for loop
PizzaOrderArray(int i)
Inside of setPizza
Inside of setPizza
Order 2:
Inside of toString
Inside of toString for loop
Inside of toString
Inside of toString for loop
PizzaOrderArray(int i)
Inside of setPizza
Inside of setPizza
Order 3:
Inside of toString
Inside of toString for loop
Inside of toString
Inside of toString for loop
PizzaOrderArray(PizzaOrderArray poa)
PizzaOrderArray(PizzaOrderArray poa) for loop
Order 4:
Inside of toString
Inside of toString for loop
Inside of toString
Inside of toString for loop
Inside of calcTotal
Inside of calcTotal for loop
Invalid pizza size
TEST: The total for order 4 is: 0.0
PizzaOrderArray(PizzaOrderArray poa)
PizzaOrderArray(PizzaOrderArray poa) for loop
Order5:
Inside of toString
Inside of toString for loop

Take a close look at the condition in this for loop, it isn't going to ever print anything since the condition is never true since i is never less than indexUsed which is 0.
public String toString() {
String s = "";
int indexUsed = 0;
System.out.println("Inside of toString");
for(int i = 0; i < indexUsed; i++)
s= (s + pizza[i].toString());
System.out.println("Inside of toString for loop");
return s;
}

Something also need pay attention to:
for(int i = 0; i < indexUsed; i++)
s= (s + pizza[i].toString());
System.out.println("Inside of toString for loop");
means:
for(int i = 0; i < indexUsed; i++) {
s= (s + pizza[i].toString());
}
System.out.println("Inside of toString for loop");
So this is System.out.println just misleading you, you are never "inside of" the for loop.
I think it's better to always use the braces '{}' with for/while loop.

The snippet
int indexUsed = 0;
System.out.println("Inside of toString");
for(int i = 0; i < indexUsed; i++)
s= (s + pizza[i].toString()); is wrong, your for loop is never executed since indexUsed is 0

In your toString method, the for loop condition never becomes true (before the first iteration itself, 0<0 becomes false & loop terminates without executing once) so the loop never executes.
You can try changing the for loop statement to:
for(int i = 0; i < index; i++)

Fix NullPointerException? [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 8 years ago.
How could I get the program to output all the information? IT currently returns a NullPointException error. Thanks.
I am supposed to use the delete methods just as they are, I cannot change them, but I am sure there must be something I can do.
public class TestCandidate7
{
public static int getTotal(Candidate[] election)
{
int total = 0;
for(Candidate candidate : election )
{
total += candidate.numVotes;
}
return total;
}
public static void printResults(Candidate[] election)
{
double percent;
System.out.println("Candidate Votes Received % of Total Votes");
for (int x = 0; x < election.length; x++)
{
percent = (double) (election[x].votes()) / getTotal(election) * 100;
System.out.printf("%-15s %10d %20.0f", election[x].getName(), election[x].votes(), percent);
System.out.println();
}
}
public static void deleteByLoc(Candidate[] election,
int location)
{
if ((location > 0) && (location < election.length))
{
//move items up in the array -
for(int index = location; index < election.length -1; index++)
election[index] = election[index + 1];
election[election.length-1] = null;
}
}
public static void deleteByName(Candidate[] election,
String find)
{
int location = 0;
int index;
// find location of item you want to delete
for(index = 0; index < election.length; index++)
if ((election[index] != null) && (election[index].getName().equals(find)))
{
location = index;
break;
}
else if (election[index] == null)
{
location = -1;
break;
}
if ((index != election.length) && (location >= 0))
{ //move items up in the array
for(index = location; index < election.length -1; index++)
election[index] = election[index + 1];
election[election.length-1] = null;
}
}
public static void main(String[] args)
{
Candidate[] election = new Candidate[10];
// create election
election[0] = new Candidate("John Smith", 5000);
election[1] = new Candidate("Mary Miller", 4000);
election[2] = new Candidate("Michael Duffy", 6000);
election[3] = new Candidate("Tim Robinson", 2500);
election[4] = new Candidate("Joe Ashtony", 1800);
election[5] = new Candidate("Mickey Jones", 3000);
election[6] = new Candidate("Rebecca Morgan", 2000);
election[7] = new Candidate("Kathleen Turner", 8000);
election[8] = new Candidate("Tory Parker", 500);
election[9] = new Candidate("Ashton Davis", 10000);
System.out.println("Original results:");
System.out.println();
printResults(election);
System.out.println();
System.out.println("Total of votes in election: " + getTotal(election) );
System.out.println();
deleteByLoc(election, 6);
System.out.println("Deleted location 6:");
System.out.println();
printResults(election);
System.out.println();
System.out.println("Total of votes in election: " + getTotal(election) );
System.out.println();
deleteByName(election, "Kathleen Turner");
System.out.println("Deleted Kathleen Turner:");
System.out.println();
printResults(election);
System.out.println();
System.out.println("Total of votes in election: " + getTotal(election) );
System.out.println();
}
}
Candidate
public class Candidate
{
// instance variables
int numVotes;
String name;
/**
* Constructor for objects of class InventoryItem
*/
public Candidate(String n, int v)
{
// initialise instance variables
name = n;
numVotes = v;
}
public int votes()
{
return numVotes;
}
public void setVotes(int num)
{
numVotes = num;
}
public String getName()
{
return name;
}
public void setName(String n)
{
name = n;
}
public String toString()
{
return name + " received " + numVotes + " votes.";
}
}

When you "delete" array elements, after the shift you assign null to the most right element of the array.
In your getTotal() you traverse the entire array and retrieve the value of numVotes for each element. When you reach the null element you are getting the exception since null does not have any fields..

How to fill a multidimensional array dependant on variables

The program I am working on is a simple shipping program. What I am having difficulty with is populating a multidimensional array factoring in certain variables.
Example
320 items need to be shipped out to 1 receiver using different box sizes.
XL can hold 50 items
LG can hold 20 items
MD can hold 5 items
SM can hold 1 items
Use the least number of boxes so far.
Code
This is my code so far.
import java.util.Scanner;
public class Shipping {
public static void main(String [] args) {
Scanner kbd = new Scanner(System.in);
final int EXTRA_LARGE = 50;
final int LARGE = 20;
final int MEDIUM = 5;
final int SMALL = 1;
String sBusinessName = "";
int iNumberOfGPS = 0;
int iShipmentCount = 0;
displayHeading(kbd);
iShipmentCount = enterShipments(kbd);
int[][] ai_NumberOfShipments = new int [iShipmentCount][4];
String[] as_BusinessNames = new String [iShipmentCount];
for (int iStepper = 0; iStepper < iShipmentCount; iStepper++) {
sBusinessName = varifyBusinessName(kbd);
as_BusinessNames[iStepper] = sBusinessName;
iNumberOfGPS = varifyGPS(kbd);
calculateBoxes(ai_NumberOfShipments[iStepper],iNumberOfGPS, EXTRA_LARGE, LARGE, MEDIUM, SMALL);
}
//showArray(as_BusinessNames);
}
public static void displayHeading(Scanner kbd) {
System.out.println("Red River Electronics");
System.out.println("Shipping System");
System.out.println("---------------");
return;
}
public static int enterShipments(Scanner kbd) {
int iShipmentCount = 0;
boolean bError = false;
do {
bError = false;
System.out.print("How many shipments to enter? ");
iShipmentCount = Integer.parseInt(kbd.nextLine());
if (iShipmentCount < 1) {
System.out.println("\n**Error** - Invalid number of shipments\n");
bError = true;
}
} while (bError == true);
return iShipmentCount;
}
public static String varifyBusinessName(Scanner kbd) {
String sBusinessName = "", sValidName = "";
do {
System.out.print("Business Name: ");
sBusinessName = kbd.nextLine();
if (sBusinessName.length() == 0) {
System.out.println("");
System.out.println("**Error** - Name is required\n");
} else if (sBusinessName.length() >= 1) {
sValidName = sBusinessName;
}
} while (sValidName == "");
return sValidName;
}
public static int varifyGPS(Scanner kbd) {
int iCheckGPS = 0;
int iValidGPS = 0;
do {
System.out.print("Enter the number of GPS receivers to ship: ");
iCheckGPS = Integer.parseInt(kbd.nextLine());
if (iCheckGPS < 1) {
System.out.println("\n**Error** - Invalid number of shipments\n");
} else if (iCheckGPS >= 1) {
iValidGPS = iCheckGPS;
}
} while(iCheckGPS < 1);
return iValidGPS;
}
public static void calculateBoxes(int[] ai_ToFill, int iNumberOfGPS) {
for (int iStepper = 0; iStepper < ai_ToFill.length; iStepper++)
}
//public static void showArray( String[] ai_ToShow) {
// for (int iStepper = 0; iStepper < ai_ToShow.length; iStepper++) {
// System.out.println("Integer at position " + iStepper + " is " + ai_ToShow[iStepper]);
// }
//}
}

Change your definition of calculateBoxes() to also take an array that represents the volume of each of the boxes (in your case this will be {50, 20, 5, 1}:
public static void calculateBoxes(int[] ai_ToFill, int[] boxVolumes, int iNumberOfGPS) {
// for each box size
for (int iStepper = 0; iStepper < ai_ToFill.length; iStepper++) {
// while the remaining items to pack is greater than the current box size
while(iNumberOfGPS >= boxVolumes[iStepper]) {
// increment the current box type
ai_ToFill[iStepper]++;
// subtract the items that just got packed
iNumberOfGPS -= boxVolumes[iStepper];
}
}
}
Another way of calculating this (using / and % instead of a while loop) would be:
public static void calculateBoxes(int[] ai_ToFill, int[] boxVolumes, int iNumberOfGPS) {
// for each box size
for (int iStepper = 0; iStepper < ai_ToFill.length; iStepper++) {
if(iNumberOfGPS >= boxVolumes[iStepper]) {
// calculate the number of boxes that could be filled by the items
ai_ToFill[iStepper] = iNumberOfGPS/boxVolumes[iStepper];
// reset the count of items to the remainder
iNumberOfGPS = iNumberOfGPS%boxVolumes[iStepper];
}
}
}

Stop method from running twice

In the method askCarType() and askSolarPanel() the inputdialog both run two times, once in their own method and once more in the final method PrintOptions().
I need them to only run once, and that is in the final method PrintOptions().
How can I do that?
import javax.swing.*;
public class short7 {
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
PrintOptions();
}// ends main
public static String askCarType() {
String typeOfCar;
typeOfCar = JOptionPane.showInputDialog("Electric or Hybrid?");
if (!typeOfCar.equals("Electric")
&& (!typeOfCar.equals("electric") && (!typeOfCar
.equals("Hybrid") && (!typeOfCar.equals("hybrid"))))) {
JOptionPane
.showMessageDialog(null,
"You have to choose either an Electric or Hybrid type of car.");
typeOfCar = JOptionPane.showInputDialog("Electric or Hybrid?");
}
return typeOfCar;
}// ends askCarType
public static String askSolarPanel() {
String wantSolarPanel;
wantSolarPanel = JOptionPane
.showInputDialog("Do you want a Solar Panel?");
if (!wantSolarPanel.equals("Yes")
&& (!wantSolarPanel.equals("yes") && (!wantSolarPanel
.equals("No") && (!wantSolarPanel.equals("no"))))) {
JOptionPane.showMessageDialog(null,
"You have to enter either Yes or No");
wantSolarPanel = JOptionPane
.showInputDialog("Do you want a Solar Panel?");
}
return wantSolarPanel;
}// ends askSolarPanel
public static int calculateDiscount() {
String typeOfCarSelected = askCarType();
String SolarPanelSelected = askSolarPanel();
int Discount = 0;
if ((typeOfCarSelected.equals("Electric") || typeOfCarSelected
.equals("electric"))
&& ((SolarPanelSelected.equals("Yes") || SolarPanelSelected
.equals("yes")))) {
Discount = 500;
} else {
Discount = 0;
}
return Discount;
}// ends calculateDiscount
public static int CalculateCost() {
String typeOfCarCost = askCarType();
String SolarPanelCost = askSolarPanel();
final int basicPrice = 20000;
final int ElectricModel = 2000;
final int SolarPanel = 5000;
final int Discount = calculateDiscount();
int total = 0;
if ((typeOfCarCost.equals("Electric") || typeOfCarCost
.equals("electric"))
&& ((SolarPanelCost.equals("No") || SolarPanelCost.equals("no")))) {
total = basicPrice + ElectricModel;
System.out.println("Basic Price:" + basicPrice);
System.out.println("Electric Model:" + ElectricModel);
System.out.println("Total:" + total);
} else if ((typeOfCarCost.equals("Electric") || typeOfCarCost
.equals("electric"))
&& ((SolarPanelCost.equals("Yes") || SolarPanelCost
.equals("yes")))) {
total = basicPrice + ElectricModel + SolarPanel - Discount;
System.out.println("Basic Price:" + basicPrice);
System.out.println("Electric Model:" + ElectricModel);
System.out.println("Solar Panel:" + SolarPanel);
System.out.println("Discount:" + Discount);
System.out.println("Total:" + total);
} else {
total += basicPrice;
System.out.println("Basic Price:" + basicPrice);
System.out.println("Total:" + total);
}
return total;
}// ends CalculateCost
public static void PrintOptions() {
CalculateCost();
}// ends PrintOptions
}// ends class short7

you're calling askCarType() and askSolarPanel() twice and what you need is call them one time !, so call them in CalculateCost() and sent the two string typeOfCarCost and SolarPanelCost to the calculateDiscount method like this :
public static int calculateDiscount(String typeOfCarSelected, String SolarPanelSelected) {
int Discount = 0;
if ((typeOfCarSelected.equals("Electric") || typeOfCarSelected.equals("electric")) && ((SolarPanelSelected.equals("Yes") || SolarPanelSelected.equals("yes")))) {
Discount = 500;
} else {
Discount = 0;
}
return Discount;
}//ends calculateDiscount
and in CalculateCost()
public static int CalculateCost() {
String typeOfCarCost = askCarType();
String SolarPanelCost = askSolarPanel();
final int basicPrice = 20000;
final int ElectricModel = 2000;
final int SolarPanel = 5000;
final int Discount = calculateDiscount(typeOfCarCost, SolarPanelCost);/////here you send the input fromthe user to this method without needing to call it again
int total = 0;
....
}

You can declare two class variables.
String typeOfCar;
String wantSolarPanel;
And in askCarType() method assign
typeOfCar = ................
and in askSolarPanel() method assign
wantSolarPanel = .....................
Then use these variables from CalculateCost() and calculateDiscount() rather than calling askCarType() and askSolarPanel() method again.