I am learning java. This is for a class that I take online. My assignment is finished.
I am trying to figure out the cause for the following.
The two main issues I have are:
1)It seems to be storing only one flower and ignoring the other inputs. How can I correct this?
2) Display flower (e.g Roses - 2):
Immediately after it displays the flowers and their count it will give me the following error message.
Flower Pack:
Daffodils - 1
Roses - 1
Exception in thread "main" java.lang.NullPointerException
at Assignment2.displayFlowers(Assignment2.java:203)
at Assignment2.<init>(Assignment2.java:44)
at Assignment2.main(Assignment2.java:9)
I believe it's origination from this statement
flowerName = searchingPack[i].getName();
Here is my code:
public class Flower {
private String name;
private String color;
private String thorns;
private String smell;
public Flower(){
}
public Flower(String flowerName, String flowerColor, String flowerThorns, String flowerSmell){
name = flowerName;
color = flowerColor;
thorns = flowerThorns;
smell = flowerSmell;
}
public String getName(){
return name;
}
public void setName(String flowerName){
name = flowerName;
}
public String getColor(){
return color;
}
public void setColor(String flowerColor){
color = flowerColor;
}
public String getThorns(){
return thorns;
}
public void setThorns(String flowerThorns){
thorns = flowerThorns;
}
public String getSmell(){
return smell;
}
public void setSmell(String flowerSmell){
smell = flowerSmell;
}
}
import java.util.Scanner;
public class Assignment2 {
public static void main(String[] args){
new Assignment2 ();
}
// This will act as our program switchboard
public Assignment2 (){
Scanner input = new Scanner(System.in);
Flower[] flowerPack = new Flower[25];
System.out.println("Welcome to my flower pack interface.");
System.out.println("Please select a number from the options below");
System.out.println("");
while(true){
// Give the user a list of their options
System.out.println("1: Add an item to the pack.");
System.out.println("2: Remove an item from the pack.");
System.out.println("3: Search for a flower.");
System.out.println("4: Display the flowers in the pack.");
System.out.println("0: Exit the flower pack interfact.");
// Get the user input
int userChoice = input.nextInt();
switch(userChoice){
case 1:
addFlower(flowerPack);
break;
case 2:
removeFlower(flowerPack);
break;
case 3:
searchFlowers(flowerPack);
break;
case 4:
displayFlowers(flowerPack);
break;
case 0:
System.out.println("Thank you for using the flower pack interface. See you again soon!");
System.exit(0);
}
}
}
//ADD FLOWERS
private void addFlower(Flower[] flowerPack) { //This is storing 1 flower but not anything else*********
Scanner add = new Scanner(System.in);
String name,color, thorns, smell;
System.out.println("\nEnter the name of the flower to add: ");
name = add.nextLine();
System.out.println("\nEnter the color of the flower: ");
color = add.nextLine();
System.out.println("\nAre there thorns present: YES or NO ");
thorns = add.nextLine();
System.out.println("\nDoes the flower smell: YES or NO ");
smell = add.nextLine();
boolean flowerInserted = false;
for(int i = 0; i < flowerPack.length; i++){
if(flowerPack[i] == null){
Flower newFlower = new Flower(name, color, thorns, smell);
flowerPack[i] = newFlower;
flowerInserted = true;
break;
}
}
if(flowerInserted){
System.out.println("Flower inserted.");
System.out.println();
}else{
System.out.println("\nFlower pack is full and could not add another flower.\n");
}
}
//REMOVE FLOWERS
private void removeFlower(Flower[] flowerPack) {
Scanner remove = new Scanner(System.in);
String removeName, removeColor;
for(int i = 0; i < flowerPack.length; i++){
System.out.println("\nEnter the name of the flower to remove: ");
removeName = remove.nextLine();
System.out.println("\nEnter the color of the flower: ");
removeColor = remove.nextLine();
if (flowerPack[i] != null)
if (flowerPack[i].getName().equalsIgnoreCase(removeName) && flowerPack[i].getColor().equalsIgnoreCase(removeColor)){
for(int j = i; j < flowerPack.length - 1; j++) {
flowerPack[j] = flowerPack[j + 1];
}
flowerPack[flowerPack.length - 1] = null;
System.out.println("\nFlower removed.\n");
break;
}
else{
System.out.println("\nThat flower was not found.\n");
}
}
}
//SEARCH FOR FLOWERS
private void searchFlowers(Flower[] flowerPack) {
Scanner flowerSearch = new Scanner(System.in);
String name, color, thorns, smell;
int options;
System.out.println("1: Seach by name.");
System.out.println("2: Seach by color.");
System.out.println("3: Seach for flowers with thorns.");
System.out.println("4: Seach for flowers that smell.");
options = flowerSearch.nextInt();
flowerSearch.nextLine();
boolean found = false;
for(int i = 0; i < flowerPack.length; i++){
if(options == 1){
System.out.println("\nEnter the name of the flower: ");
name = flowerSearch.nextLine();
if (flowerPack[i] != null) {
if (flowerPack[i].getName().equalsIgnoreCase(name)) {
found = true;
System.out.println("\nFlower was found at index " + i + ".");
break;
}
}
}
if(options == 2){
System.out.println("\nEnter the color of the flower: ");
color = flowerSearch.nextLine();
if (flowerPack[i] != null) {
if (flowerPack[i].getColor().equalsIgnoreCase(color)) {
found = true;
System.out.println("\nFlower was found at index " + i + ".");
break;
}
}
}
if(options == 3){
System.out.println("\nFlowers with thorns or no thorns: YES or NO ");
thorns = flowerSearch.nextLine();
if (flowerPack[i] != null) {
if (flowerPack[i].getThorns().equalsIgnoreCase(thorns)) {
found = true;
System.out.println("\nFlower was found at index " + i + ".");
break;
}
}
}
if(options ==4){
System.out.println("\nFlower with aroma or no aroma: YES or NO ");
smell = flowerSearch.nextLine();
if (flowerPack[i] != null) {
if (flowerPack[i].getSmell().equalsIgnoreCase(smell)) {
found = true;
System.out.println("\nFlower was found at index " + i + ".");
break;
}
}
}
if(!found){
System.out.println("\nSorry, no match found.");
}
}
}
//DISPLAY FLOWERS
private void displayFlowers(Flower[] flowerPack) {
System.out.println("Flower Pack: \n");
Flower[] searchingPack = new Flower[flowerPack.length];
for (int i = 0; i < searchingPack.length; i++) {
searchingPack[i] = flowerPack[i];
}
String flowerName = null;
int count = 0;
for(int i = 0; i < searchingPack.length; i++) {
i = 0;
flowerName = searchingPack[i].getName(); // this line is giving me an error!***********************************
if (searchingPack[i].getName() == null || searchingPack[i].getName().equals(null)) {
break;
}
for (int j = 0; j < flowerPack.length; j++) {
if (flowerPack[j] != null) {
if (flowerPack[j].getName().equalsIgnoreCase(flowerName)) {
count++;
}
}
}
for (int k = 0; k < count; k++) {
silentRemove(searchingPack, flowerName);
}
System.out.println(flowerName + " - " + count);
System.out.println();
count = 0;
}
}
private void silentRemove(Flower flowerPack[], String flowerName) {
for (int i = 0; i < flowerPack.length; i++) {
if (flowerPack[i] != null) {
if (flowerPack[i].getName().equalsIgnoreCase(flowerName)) {
for (int j = i; j < flowerPack.length - 1; j++) {
flowerPack[j] = flowerPack[j + 1];
}
flowerPack[flowerPack.length - 1] = null;
break;
}
}
}
}
}
Does it need to be an array? A List<Flower> is more appropriate here. What is happening is you're only adding 2 flowers, but looping over all 25 elements in the array, some of which are still null
The problem is with
flowerName = searchingPack[i].getName();
because searchingPack[i] might be null and then you're trying to reach an address that doesn't exists.
do something like this:
if(searchingPack[i]==null)
flowerName="";
else
flowerName = searchingPack[i].getName();
If you are planning on doing the same kinds of actions you might consider putting an "empty" flower at each index in the array so it won't throw an error.
Related
The problem I have encountered is as follows: I have created two arrays representing docking spaces for ships. The first array the ship object (shipName and size - usually Super-Container) can be saved in the array and if there is no space then it will be added to a waiting list array.
I can only add one ship to the waiting list and it says it is full.
Can you help? Here's my dock class, problem in waitingList():
import java.util.*;
public class Main {
static Scanner scan = new Scanner(System.in);
private static Ship[] dock1 = new Ship[10];
private static Ship[] waitingList = new Ship[10];
public static void main(String[] args) {
menu();
}
public static void menu() {
Scanner scan = new Scanner(System.in);
while (true) {
System.out.println("Choose an option: 1-3");
System.out.println("1. Dock");
System.out.println("2. Undock");
System.out.println("3. Status");
int menu = scan.nextInt();
switch (menu) {
case 1:
System.out.println("1. Dock");
dock();
break;
case 2:
System.out.println("2. Undock");
undock();
break;
case 3:
System.out.println("3. Status");
printDock();
printWaitingList();
break;
case 4:
System.out.println("4. Exit");
System.exit(0);
default:
System.out.println("No such option");
break;
}
}
}
public static void dock() {
System.out.println("Enter ship's name: ");
String name = scan.nextLine();
System.out.println("Enter ship's size: ");
String size = scan.nextLine();
System.out.println("Enter the ships dock:");
//Check if the dock number is valid
int i = Integer.valueOf(scan.nextLine());
if (i >= 0 && i < 10 && dock1[i] == null) {
int c = 0;
int co = 0;
int sco = 0;
for (int j = 0; j < dock1.length; j++) {
if (dock1[j] != null && dock1[j].getShipSize().equals("Cargo")) {
c++;
}
if (dock1[j] != null && dock1[j].getShipSize().equals("Container")) {
co++;
}
if (dock1[j] != null && dock1[j].getShipSize().equals("Super-Container")) {
sco++;
}
}
if (c < 10 && co < 5 && sco < 2) {
//Add ship to the dock
dock1[i] = new Ship(name, size);
System.out.println("Enough space you can dock");
System.out.println("Ship has been docked");
} else {
System.out.println("You cannot dock");
waitingList(name,size);
}
} else {
System.out.println("Couldn't dock");
waitingList(name, size);
}
}
public static void undock() {
System.out.println("Status of ships: ");
printDock();
System.out.println("Enter ship's name to undock: ");
String name = scan.nextLine();
//System.out.println("Enter ship's size to undock: ");
// String size = scan.nextLine();
for (int i = 0; i < dock1.length; i++) {
if (dock1[i] != null && dock1[i].getShipName().equals(name)) {
dock1[i] = null;
System.out.println("Ship removed");
/// HERE CHECK IF SHIP IN DOCK
for (int j = 0; j < waitingList.length; j++) {
if (dock1[i] == null) {
// Add ship to the dock
dock1[i] = new Ship(waitingList[j].getShipName(), waitingList[j].getShipSize());
System.out.println("Move ship from waiting list to dock 1");
waitingList[j] = null;
break;
} else {
System.out.println("No space in dock1");
return;
}
}
} else {
System.out.println("Ship not docked here");
break;
}
}
}
public static void waitingList(String name, String size){
System.out.println("Dock 1 is full, ship will try to be added to Waiting List");
for (int i = 0; i < waitingList.length; i++) {
if (waitingList[i] == null) { //CHANGE TO ALLOW MORE THAN ONE SHIP
//Add ship to the dock
waitingList[i] = new Ship(name, size);
System.out.println("Enough space added to waiting list");
break;
} else {
System.out.println("No space on waiting list, ship turned away");
return;
}
}
}
public static void printDock() {
System.out.println("Docks:");
for (int i = 0; i < dock1.length; i++) {
if (dock1[i] == null) {
System.out.println("Dock " + i + " is empty");
} else {
System.out.println("Dock " + i + ": " + dock1[i].getShipName() + " " + dock1[i].getShipSize());
}
}
}
private static void printWaitingList() {
System.out.println("Waiting List:");
for (int i = 0; i < waitingList.length; i++) {
if (waitingList[i] == null) {
System.out.println("Dock " + i + " is empty");
} else {
System.out.println("Dock " + i + ": " + waitingList[i].getShipName() + " " + waitingList[i].getShipSize());
}
}
}
}
Try this:
public static void waitingList(String name, String size){
System.out.println("Dock 1 is full, ship will try to be added to Waiting List");
for (int i = 0; i < waitingList.length; i++) {
if (waitingList[i] == null) {
//Add ship to the dock
waitingList[i] = new Ship(name, size);
System.out.println("Enough space. Added to waiting list.");
return;
} else {
System.out.println("No space on waiting list at number "+ i +", checking next space."); //Optional
}
}
// Only when no spaces available
System.out.println("No space on waiting list, ship turned away.");
}
if you add a ship to the waitingList array, it will not be null never again, so that check (if waitingList[0] == null) will result into executing the else part, where it is a return, so the loop will not continue and will never try to check if waitingList[1] == null.
So, the solution is to exit the method when the ship is added to the list, not when we see the first used space. So changeing the return will help.
The problem I have encountered is as follows: I have created two array representing docking spaces for ships. The first array the ship object (shipName and size - usually Super-Container) be saved in the array and if there is no space then it will be added to a waiting list array. If the space in the first array becomes vacant then the ship from the waiting list will join the first array.
But when I go to undock (remove a ship from the first array) it only finds the ship in index 0 of the first array and not index 1, 2 etc.
Also, I can only add one ship to the waiting list and it says it is full.
Can you help? Here's my dock class, problem in undock() and waitingList():
import java.util.*;
public class Main {
static Scanner scan = new Scanner(System.in);
private static Ship[] dock1 = new Ship[10];
private static Ship[] waitingList = new Ship[10];
public static void main(String[] args) {
menu();
}
public static void menu() {
Scanner scan = new Scanner(System.in);
while (true) {
System.out.println("Choose an option: 1-3");
System.out.println("1. Dock");
System.out.println("2. Undock");
System.out.println("3. Status");
int menu = scan.nextInt();
switch (menu) {
case 1:
System.out.println("1. Dock");
dock();
break;
case 2:
System.out.println("2. Undock");
undock();
break;
case 3:
System.out.println("3. Status");
printDock();
printWaitingList();
break;
case 4:
System.out.println("4. Exit");
System.exit(0);
default:
System.out.println("No such option");
break;
}
}
}
public static void dock() {
System.out.println("Enter ship's name: ");
String name = scan.nextLine();
System.out.println("Enter ship's size: ");
String size = scan.nextLine();
System.out.println("Enter the ships dock:");
//Check if the dock number is valid
int i = Integer.valueOf(scan.nextLine());
if (i >= 0 && i < 10 && dock1[i] == null) {
int c = 0;
int co = 0;
int sco = 0;
for (int j = 0; j < dock1.length; j++) {
if (dock1[j] != null && dock1[j].getShipSize().equals("Cargo")) {
c++;
}
if (dock1[j] != null && dock1[j].getShipSize().equals("Container")) {
co++;
}
if (dock1[j] != null && dock1[j].getShipSize().equals("Super-Container")) {
sco++;
}
}
if (c < 10 && co < 5 && sco < 2) {
//Add ship to the dock
dock1[i] = new Ship(name, size);
System.out.println("Enough space you can dock");
System.out.println("Ship has been docked");
} else {
System.out.println("You cannot dock");
waitingList(name,size);
}
} else {
System.out.println("Couldn't dock");
waitingList(name, size);
}
}
public static void undock() {
System.out.println("Status of ships: ");
printDock();
System.out.println("Enter ship's name to undock: ");
String name = scan.nextLine();
//System.out.println("Enter ship's size to undock: ");
// String size = scan.nextLine();
for (int i = 0; i < dock1.length; i++) {
if (dock1[i] != null && dock1[i].getShipName().equals(name)) {
dock1[i] = null;
System.out.println("Ship removed");
/// HERE CHECK IF SHIP IN DOCK
for (int j = 0; j < waitingList.length; j++) {
if (dock1[i] == null) {
// Add ship to the dock
dock1[i] = new Ship(waitingList[j].getShipName(), waitingList[j].getShipSize());
System.out.println("Move ship from waiting list to dock 1");
waitingList[j] = null;
break;
} else {
System.out.println("No space in dock1");
return;
}
}
} else {
System.out.println("Ship not docked here");
break;
}
}
}
public static void waitingList(String name, String size){
System.out.println("Dock 1 is full, ship will try to be added to Waiting List");
for (int i = 0; i < waitingList.length; i++) {
if (waitingList[i] == null) { //CHANGE TO ALLOW MORE THAN ONE SHIP
//Add ship to the dock
waitingList[i] = new Ship(name, size);
System.out.println("Enough space added to waiting list");
break;
} else {
System.out.println("No space on waiting list, ship turned away");
return;
}
}
}
public static void printDock() {
System.out.println("Docks:");
for (int i = 0; i < dock1.length; i++) {
if (dock1[i] == null) {
System.out.println("Dock " + i + " is empty");
} else {
System.out.println("Dock " + i + ": " + dock1[i].getShipName() + " " + dock1[i].getShipSize());
}
}
}
private static void printWaitingList() {
System.out.println("Waiting List:");
for (int i = 0; i < waitingList.length; i++) {
if (waitingList[i] == null) {
System.out.println("Dock " + i + " is empty");
} else {
System.out.println("Dock " + i + ": " + waitingList[i].getShipName() + " " + waitingList[i].getShipSize());
}
}
}
}
Your loops are only working with first element of the array, becouse when check failed (for example if (waitingList[i] == null) in waitingList) you print error, and then return, thus breaking loop. What you need to do is make boolean dockSuccessful = false, then if condition is met (there is space in dock) you set it to true and then break the loop (so you woudn't dock ship multiple times). After the loop you insert
if(!dockSuccessful) {
System.out.println("Some error message here");
}
So, if loop finds at least one empty dock, dockSuccessful would be true, and error would not be printed. But if it checked all the docks, it will not update dockSuccessful, it would still be false, and error will be printed.
The problem I have encountered is as follows: I have created 10 row outputs representing docking spaces for ships.
But the dock can accommodate two sizes of ship; cargo and container. The rows are made up of 5 small and 5 medium. A cargo ship (small) can berth in any available space. A container ship (medium) can berth in the medium space, but not in small spaces.
So if I enter shipName and Container for example it searches the array making sure there is less than 5 Container's so it can dock i.e. save in the array. Can you help?
Here's my dock method:
import java.util.*;
public class Main {
static Scanner scan = new Scanner(System.in);
private static Ship[] dock1 = new Ship[10];
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
while(true) {
System.out.println("Choose an option: 1-3");
System.out.println("1. Dock");
System.out.println("2. Undock");
System.out.println("3. Status");
int menu = scan.nextInt();
switch (menu) {
case 1:
System.out.println("1. Dock");
dock();
break;
case 2:
System.out.println("2. Undock");
undock();
break;
case 3:
System.out.println("3. Status");
printArray();
break;
case 4:
System.out.println("4. Exit");
System.exit(0);
default:
System.out.println("No such option");
break;
}
}
}
public static void dock() {
int dockCapacity = 0;
System.out.println("Enter ship's name: ");
String name = scan.nextLine();
System.out.println("Enter ship's size: ");
String size = scan.nextLine();
System.out.println("Enter the ships dock:");
//search for 5 small 3 med 2 large
// if what they entered equals shipSize more than 5 than cannot dock.
for(int i = 1; i < dock1.length; i++) {
if (dock1[i].getShipSize().equals(size)) {
System.out.print(dock1[i].getShipSize());
}
else {
System.out.println("Couldn't dock");
}
}
//Check if the dock number is valid
int i = Integer.valueOf(scan.nextLine());
if (i >= 0 && i < 10 && dock1[i] == null){
//Add ship to the dock
dock1[i] = new Ship(name, size);
System.out.println("Ship has been docked");
}
else{
System.out.println("Couldn't dock");
}
// printArray();
}
public static void undock(){
System.out.println("Status of ships: ");
printArray();
System.out.println("Enter ship's name to undock: ");
String name = scan.nextLine();
for(int i = 1; i < dock1.length; i++){
if(dock1[i] != null && dock1[i].getShipName().equals(name)){
dock1[i] = null;
System.out.println("Ship removed");
break;
}
else{
System.out.println("Ship not docked here");
}
}
}
public static void printArray() {
System.out.println("Docks:");
for(int i = 0; i < dock1.length; i++)
{
if(dock1[i] == null)
{
System.out.println("Dock " + i + " is empty");
}
else
{
System.out.println("Dock " + i + ": " + dock1[i].getShipName() + " " + dock1[i].getShipSize());
}
}
}
}
Ship class
public class Ship {
private String shipName;
private String shipSize;
public String getShipName() {
return shipName;
}
public void setShipName(String shipName) {
this.shipName = shipName;
}
public String getShipSize() {
return shipSize;
}
public void setShipSize(String shipSize) {
this.shipSize = shipSize;
}
public Ship(String shipName, String shipSize) {
this.shipName = shipName;
this.shipSize = shipSize;
}
}
I would recommend you to change the Ship class like this. It adds a ShipSize enum and makes it much easier to parse the ship size from string and compare ship sizes. Also, I added a isCargo and isContainer method.
import java.util.Arrays;
public class Ship {
private String shipName;
private ShipSize shipSize;
public Ship(String shipName, ShipSize shipSize) {
this.shipName = shipName;
this.shipSize = shipSize;
}
public String getShipName() {
return shipName;
}
public void setShipName(String shipName) {
this.shipName = shipName;
}
public ShipSize getShipSize() {
return shipSize;
}
public void setShipSize(ShipSize shipSize) {
this.shipSize = shipSize;
}
public boolean isCargo() {
return shipSize == ShipSize.CARGO;
}
public boolean isContainer() {
return shipSize == ShipSize.CONTAINER;
}
public enum ShipSize {
CARGO,
CONTAINER;
public static ShipSize of(String size) {
return Arrays.stream(ShipSize.values()).filter(enumSize -> enumSize.name().equalsIgnoreCase(size)).findAny().orElse(null);
}
}
}
I also modified your main class so it does what you want. I added some parsing and checks for the numbers, added an initialize method for the docks.
import java.util.*;
public class Main {
static Scanner scan = new Scanner(System.in);
private static Dock[] dock1 = new Dock[10];
public static void main(String[] args) {
initializeDock();
Scanner scan = new Scanner(System.in);
while(true) {
System.out.println("Choose an option: 1-3");
System.out.println("1. Dock");
System.out.println("2. Undock");
System.out.println("3. Status");
int menu = scan.nextInt();
switch (menu) {
case 1:
System.out.println("1. Dock");
dock();
break;
case 2:
System.out.println("2. Undock");
undock();
break;
case 3:
System.out.println("3. Status");
printArray();
break;
case 4:
System.out.println("4. Exit");
System.exit(0);
default:
System.out.println("No such option");
break;
}
}
}
private static void initializeDock() {
for (int i = 0; i < 5; i++) {
dock1[i] = new Dock(Ship.ShipSize.CARGO);
}
for (int i = 5; i < 10; i++) {
dock1[i] = new Dock(Ship.ShipSize.CONTAINER);
}
}
public static void dock() {
int dockCapacity = 0;
System.out.println("Enter ship's name: ");
String name = scan.nextLine();
Ship.ShipSize size = null;
while(size == null) {
System.out.println("Enter ship's size: ");
String stringSize = scan.nextLine();
size = Ship.ShipSize.of(stringSize);
if (size == null) {
System.out.println("Could not read ship size. Only cargo and container are allowed.");
}
}
// check that ship fits into any dock
if (size == Ship.ShipSize.CONTAINER) {
long numberOfContainerShips = Arrays.stream(dock1).map(Dock::getDockedShip).filter(Objects::nonNull).filter(Ship::isContainer).count();
if (numberOfContainerShips >= 5) {
System.out.println("No place for a ship that large. Aborting.");
return;
}
}
System.out.println("Enter the ships dock:");
Integer dockNumber = null;
while(dockNumber == null) {
dockNumber = scan.nextInt();
if (dockNumber < 0 || dockNumber > dock1.length - 1) {
System.out.println("Illegal dock number. Only numbers between 0 and " + dock1.length + " are allowed.");
dockNumber = null;
}
}
Dock dock = dock1[dockNumber];
if (dock.getDockedShip() != null) {
System.out.println("Dock reserved - couldn't dock");
return;
}
if (dock.getSupportedSize() == Ship.ShipSize.CARGO && size == Ship.ShipSize.CONTAINER) {
System.out.println("Dock too small - couldn't dock");
return;
}
dock.setDockedShip(new Ship(name, size));
}
public static void undock(){
System.out.println("Status of ships: ");
printArray();
System.out.println("Enter ship's name to undock: ");
String name = scan.nextLine();
for(int i = 1; i < dock1.length; i++){
if(dock1[i].getDockedShip() != null && dock1[i].getDockedShip().getShipName().equals(name)){
dock1[i] = null;
System.out.println("Ship removed");
break;
}
else{
System.out.println("Ship not docked here");
}
}
}
public static void printArray() {
System.out.println("Docks:");
for(int i = 0; i < dock1.length; i++)
{
if(dock1[i].getDockedShip() == null)
{
System.out.println("Dock " + i + " is empty. Size: " + dock1[i].getSupportedSize().name().toLowerCase());
}
else
{
System.out.println("Dock " + i + ": " + dock1[i].getDockedShip().getShipName() + " " + dock1[i].getDockedShip().getShipSize().name().toLowerCase());
}
}
}
}
I also added a Dock class. It works fine.
public class Dock {
private Ship.ShipSize supportedSize;
private Ship dockedShip = null;
public Dock(Ship.ShipSize supportedSize) {
this.supportedSize = supportedSize;
}
public Ship.ShipSize getSupportedSize() {
return supportedSize;
}
public void setSupportedSize(Ship.ShipSize supportedSize) {
this.supportedSize = supportedSize;
}
public Ship getDockedShip() {
return dockedShip;
}
public void setDockedShip(Ship dockedShip) {
this.dockedShip = dockedShip;
}
}
Currently, I'm trying to read in a .dat file and assign various lines into an array. The file will provide items like "a100" and "q80" which I will have to separate into categories by letter and then have different grades as an array for each category. Right now, this is what I have, but I'm getting a lot of run-time errors when I try various things. Is there something I'm missing here?
Some of the errors I'm having:
When I execute case 'P', it prints this out: WeightedGrades#13105f32
When I try to execute cases C, A or D, this happens: Exception in thread "main" java.lang.NoSuchMethodError: WeightedGrades.deleteGrade(Ljava/lang/String;)Z
WeightedGrades class:
public class WeightedGrades {
private String name;
private int numGrades;
private String[] grades;
public static final double ACTV_WT = 0.05, QUIZ_WT = 0.10, PROJ_WT = 0.25, EXAM_WT = 0.30, FINAL_EXAM_WT = 0.30;
public WeightedGrades(String nameIn, int numGradesIn, String[] gradesIn) {
name = nameIn;
numGrades = numGradesIn;
grades = gradesIn;
}
public String getName() {
return name;
}
public int getNumGrades() {
return numGrades;
}
public String[] getGrades() {
return grades;
}
public double[] gradesByCategory(char categoryChar) {
int count = 0;
for (int i = 0; i < grades.length; i++) {
if (categoryChar == grades[i].charAt(0)) {
count++;
}
}
double[] gradesNew = new double[count];
count = 0;
for( int i = 0; i < numGrades; i++) {
if (categoryChar == grades[i].charAt(0)) {
gradesNew[count] = Double.parseDouble(grades[i].substring(1));
count++;
}
}
return gradesNew;
}
public String toString() {
String result = "\tStudent Name: " + getName()
+ "\n\tActivities: " + gradesByCategory('A')
+ "\n\tQuizzes: " + gradesByCategory('Q')
+ "\n\tProjects: " + gradesByCategory('P')
+ "\n\tExams: " + gradesByCategory('E')
+ "\n\tFinal Exam: " + gradesByCategory('F')
+ "\n\tCourse Average: " + courseAvg();
return result;
}
public void addGrade(String newGrade) {
if (numGrades >= grades.length) {
increaseGradesCapacity();
}
grades[numGrades] = newGrade;
numGrades++;
}
public boolean deleteGrade(String gradeDelete) {
boolean delete = false;
int deleteIndex = -1;
for (int i = 0; i < numGrades; i++) {
if (gradeDelete.charAt(0) == grades[i].charAt(0) &&
Double.parseDouble(gradeDelete.substring(1))
== Double.parseDouble(grades[i].substring(1))) {
deleteIndex = i;
}
}
if (deleteIndex > -1) {
for (int i = deleteIndex; i < numGrades - 1; i++) {
grades[i] = grades[i + 1];
}
grades[numGrades - 1] = "";
numGrades--;
return true;
}
else {
return false;
}
}
public void increaseGradesCapacity() {
String[] temporary = new String[grades.length + 1];
for (int i = 0; i < grades.length; i++) {
temporary[i] = grades[i];
}
grades = temporary;
}
public double average(double[] newArray) {
if (newArray.length == 0) {
return 0.0;
}
double sum = 0;
double average = 0;
for ( int i = 0; i < newArray.length; i++) {
sum += newArray[i];
average = sum / newArray.length;
}
return average;
}
public double courseAvg() {
double actvAvg = 0.0;
double quizAvg = 0.0;
double projAvg = 0.0;
double examAvg = 0.0;
double finalAvg = 0.0;
double avg = 0.0;
if (!numGrades.length == 0) {
avg = actvAvg * ACTV_WT + quizAvg * QUIZ_WT + projAvg * PROJ_WT + examAvg * EXAM_WT + finalAvg * FINAL_EXAM_WT;
}
return avg;
}
}
Second class
import java.util.Scanner;
import java.io.IOException;
public class WeightedGradesApp {
public static void main(String[] args) throws IOException {
String name = "";
int numGrades = 0;
String[] grades = new String[13];
String code = "";
String gradeAdd = "";
String gradeDelete = "";
String categoryIn = "";
WeightedGrades student = new WeightedGrades(name, numGrades, grades);
Scanner userInput = new Scanner(System.in);
if (args == null) {
System.out.println("File name was expected as a run argument.");
System.out.println("Program ending.");
return;
}
else {
System.out.println("File read in and WeightedGrades object created.");
System.out.println("");
System.out.println("Player App Menu");
System.out.println("P - Print Report");
System.out.println("C - Print Category");
System.out.println("A - Add Grade");
System.out.println("D - Delete Grade");
System.out.println("Q - Quit ");
do {
System.out.print("Enter Code [P, C, A, D, or Q]: ");
code = userInput.nextLine();
if (code.length() == 0) {
continue;
}
code = code.toUpperCase();
char codeChar = code.charAt(0);
switch (codeChar) {
case 'P':
System.out.println(student.toString());
break;
case 'C':
System.out.print(" Category: ");
categoryIn = userInput.nextLine();
char categoryChar = categoryIn.charAt(0);
System.out.println(student.gradesByCategory(categoryChar));
break;
case 'A':
System.out.print(" Grade to add: ");
gradeAdd = userInput.nextLine();
student.addGrade(gradeAdd);
break;
case 'D':
System.out.print(" Grade to delete: ");
gradeDelete = userInput.nextLine();
boolean isDeleted = student.deleteGrade(gradeDelete);
if (isDeleted) {
System.out.println(" Grade deleted");
}
else {
System.out.println(" Grade not found");
}
break;
case 'Q':
break;
default:
}
} while (!code.equalsIgnoreCase("Q"));
}
}
}
For starters your code as is doesn't compile due to the line
if (!numGrades.length == 0) {
This is because numGrades is an int it is a primative type and therefore does not have any property length. I'm assuming what you want here is
if (numGrades != 0) {
Also as I mentioned you are not dealing with reading in the file, you supply the file name but never actually read it, I suggest you look at the Java tutorial on File IO
On this note you do the check args == null this will not check that no args are supplied, try it. what you want is args.length == 0
On your other error I have no idea how you even produced that... I'm assuming it is using an older compiled version of the class where the methods have not being written.
This is very interesting, i notice. Before i can explain further its best i show the code and you will understand what i mean.
This is the code:
public class Qn3 {
static BigDecimal[] accbal = new BigDecimal[19];
private static Integer[] accnums = new Integer[19];
public static void main(String[] args) {
addaccount();
}
public static void addAccount() {
int i = 0, accno, input, j, check;
BigDecimal accbala;
DecimalFormat df = new DecimalFormat("0.00");
Scanner sc = new Scanner(System.in);
Scanner in = new Scanner(System.in);
accnums[1] = new Integer(1);
while (accnums.length >= count(accnums)) {
System.out.print("Enter the account number: ");
while (sc.hasNext("[0-9]{7}")) {
accno = sc.nextInt();
System.out.print("Enter account balance: ");
accbala = in.nextBigDecimal();
for (j = 0; j < accnums.length; j++) {
if (accnums[j] == null)
break;
else if (accnums[j].equals(accno)) {
break;
}
}
if (j == accnums.length) {
System.out.print("No more than 20 accounts can be added.");
} else if (accnums[j] != null) {
if ((accnums[j].equals(accno)))
System.out.println("Account already exists");
break;
} else {
accnums[j] = accno;
accbala = accbala.setScale(2, RoundingMode.HALF_UP);
accbal[j] = accbala;
check = j;
System.out.println("Current number of accounts in the system: "
+ (check + 1)
+ "\nNumber of accounts still can be added: "
+ (20 - (check + 1)));
}
}
while (!sc.hasNext("[0-9]{7}")) {
System.out.println("Wrong NRIC");
break;
}
while (accnums.length <= count(accnums)) {
System.out.println("20 accounts have already been created");
break;
}
break;
}
}
private static int count(Integer[] array) {
int count = 0;
// accnums = new Integer[] {1,2};
for (int index = 0; index < array.length; index++) {
if (array[index] != null) {
count++;
}
}
// System.out.println("You have used " + count + " slots");
return count;
}
}
So now that you have seen the code the problem that is hard to notice is this, take note of the line in the addaccount() method where
System.out.println("Current number of accounts in the system: "+(check+1)+"\nNumber of accounts still can be added: "+(20 - (check+1)));
this line the first check+1 will give me 1 then the next one gives me 3! and then the next time i run the method it gives me 4 and then again 5 and so on so forth, what is happening to 2?
You have that println in an else block, and when j == 1 you're hitting the else if case. Try removing this line
accnums[1] = new Integer (1);