Develop Reference

Retrieve lines in txt file and append new inputs from the user java

I'm using an arraylist to append inputs and send the arraylist elements to file. However, everytime I exit the program and run it again, the contents in the written in the file becomes empty.
ArrayList<String> memory = new ArrayList<String>();
public void fileHandling() {
try {
FileWriter fWriter = new FileWriter("notes.data");
for (int x = 0; x <= memory.size() - 1; x++) {
fWriter.write(memory.get(x) + '\n');
}
fWriter.close();
} catch (IOException e) {
System.out.println(e);
}
}
public void createNote() {
Scanner insertNote = new Scanner(System.in);
LocalDate todayDate = LocalDate.now();
LocalTime nowTime = LocalTime.now();
String timeFormat = nowTime.format(DateTimeFormatter.ofLocalizedTime(FormatStyle.MEDIUM));
String dateTime = todayDate.toString() + " at " + timeFormat;
while (true) {
System.out.println();
System.out.println("Enter a note");
System.out.print("> ");
String note = insertNote.nextLine();
if (note == null) {
System.out.println("Invalid input! Try again");
break;
} else {
memory.add(note + " /" + dateTime);
fileHandling();
System.out.println("Note is saved!\n");
break;
}
}
I expect the program to save the contents of every input. Then if I exit and run the program again, the contents will go back to the array

Your code currently does the following:
You enter something (X) for the first time:
It gets added to the ArrayList
The ArrayList gets written into the file
Your file now contains: X
You enter something second (Y):
It gets added to the ArrayList (Which now contains: X, Y)
The ArrayList gets written into the file
Your file now contains: X + newline + Y
Your Problem is, that everytime you create a new FileWrite it overwrites your file.
This can be avoided by using the constructor like this:
FileWriter writer = new FileWriter("notes.data", true);
This sets it into the append mode and therefore keeps previous data in the file

You don't need to create a separate Scanner, in method createNote(), in order to get a "note" from the user.
It is usually better to write your code using the interface rather than the specific implementation because then you usually need to change less code if you decide to change the implementation. Hence the type for member variable memory should probably be List rather than ArrayList.
Note that ArrayList may waste memory if the list of "note"s is large. I suggest using LinkedList instead. Alternatively, use an array (rather than a List) and handle expanding the array when adding a "note" as well as reducing the array when removing a "note".
Having an infinite loop, i.e. while (true), which contains a single if-else where both the if block and the else block contain break statements, means that the loop will perform exactly one iteration. May as well remove the while loop – which means also removing the break statements.
Rather than writing the code that generates a timestamp repeatedly, you should adopt the DRY principle and extract that code into a separate method.
The file name should be a constant so as to minimize the amount of code changes you will need to do if you decide to change the file name.
By convention, text files have a filename extension of .txt whereas binary files have the .data extension.
Although you don't need to, I personally prefer to initialize class member variables in the constructor.
The below code is a SSCCE, hence I added a main method. More notes appear after the code.
package Methods;
import java.util.*;
import java.time.format.*;
import java.time.*;
import java.io.*;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
public class FileSys {
private static final String FILENAME = "notes.txt";
private static final String CREATE = "C";
private static final String DELETE = "D";
private static final String FIND = "F";
private static final String QUIT = "Q";
private static final String SHOW = "S";
private static final String UPDATE = "U";
Scanner reader;
List<String> memory;
public FileSys() throws IOException {
reader = new Scanner(System.in);
memory = new LinkedList<String>();
loadFile();
}
public void fileHandling() {
Path path = Paths.get(FILENAME);
try (BufferedWriter bw = Files.newBufferedWriter(path,
StandardOpenOption.CREATE,
StandardOpenOption.WRITE);
PrintWriter pw = new PrintWriter(bw)) {
for (String write : memory) {
pw.println(write);
}
}
catch (IOException e) {
e.printStackTrace();
}
}
public void createNote() {
String dateTime = getTimestamp();
System.out.println();
System.out.println("Enter a note");
System.out.print("> ");
String note = reader.nextLine();
memory.add(note + " / " + dateTime);
fileHandling();
System.out.println("Note is saved!");
}
public void searchNote() {
System.out.print("\nEnter note number: ");
try {
int search = reader.nextInt();
reader.nextLine();
System.out.println("\nSearch result:");
int index = memory.indexOf(memory.get(search - 1));
if (index != -1) {
System.out.println("[" + (index + 1) + "]" + " " + memory.get(search - 1));
}
else {
System.out.println("Note number-" + search + " is not found in the collection!");
}
}
catch (IndexOutOfBoundsException e) {
System.out.println("The note number you have entered is invalid!");
}
}
public void updateNote() {
String dateTime = getTimestamp(); // ZonedDateTime.now(ZoneId.systemDefault()).format(dateTimeObj);
System.out.print("\nEnter note number to change: ");
try {
int search = reader.nextInt();
int index = memory.indexOf(memory.get(search - 1));
String updateLine;
if (index != -1) {
System.out.println("\nCurrent note: ");
System.out.println("[" + (index + 1) + "]" + " " + memory.get(search - 1));
System.out.println("\nThe updated note will be: ");
System.out.print("> ");
reader.nextLine();
updateLine = reader.nextLine();
memory.set(index, updateLine + " /" + dateTime);
System.out.print("Note has been updated successfully!\n");
}
else {
System.out.println(search + " is not found in the collection!");
}
}
catch (IndexOutOfBoundsException e) {
System.out.println("The note number you have entered is invalid!");
}
fileHandling();
}
public void deleteNote() {
System.out.print("\nEnter note number to delete: ");
try {
int search = reader.nextInt();
reader.nextLine();
int index = memory.indexOf(memory.get(search - 1));
System.out.println();
if (index != -1) {
System.out.println("[" + (index + 1) + "]" + " " + memory.get(search - 1));
System.out.print("\nDo you want to delete this note? \n[y] or [n]: ");
char delDecision = reader.nextLine().charAt(0);
if (delDecision == 'y' || delDecision == 'Y') {
memory.remove(index);
System.out.println("Note has been deleted successfully!");
System.out.println();
}
else if (delDecision == 'n' || delDecision == 'N') {
System.out.println("Note was not deleted!");
}
else {
System.out.println("Invalid input!");
}
}
else {
System.out.println(search + " is not found in the collection!");
}
}
catch (IndexOutOfBoundsException e) {
System.out.println("The note number you have entered is invalid!");
}
fileHandling();
}
public void displayNote() {
if (memory.size() > 0) {
int counter = 0;
for (String note : memory) {
System.out.printf("%d. %s%n", ++counter, note);
}
}
else {
System.out.println("There are no notes.");
}
}
private String getTimestamp() {
LocalDate todayDate = LocalDate.now();
LocalTime nowTime = LocalTime.now();
String timeFormat = nowTime.format(DateTimeFormatter.ofLocalizedTime(FormatStyle.MEDIUM));
String dateTime = todayDate.toString() + " at " + timeFormat;// ZonedDateTime.now(ZoneId.systemDefault()).format(dateTimeObj);
return dateTime;
}
private void loadFile() throws IOException {
Path path = Paths.get(FILENAME);
if (Files.isRegularFile(path)) {
memory.addAll(Files.readAllLines(path, Charset.defaultCharset()));
}
}
private void showMenu() {
String choice = "";
while (!QUIT.equalsIgnoreCase(choice)) {
System.out.println(CREATE + " - Create note");
System.out.println(DELETE + " - Delete note");
System.out.println(FIND + " - Search notes");
System.out.println(SHOW + " - Show notes");
System.out.println(UPDATE + " - Update note");
System.out.println(QUIT + " - Quit");
System.out.println();
System.out.print("Your choice: ");
choice = reader.nextLine();
if (!choice.isEmpty()) {
choice = choice.substring(0, 1);
choice = choice.toUpperCase();
switch (choice) {
case CREATE -> createNote();
case DELETE -> deleteNote();
case FIND -> searchNote();
case SHOW -> displayNote();
case UPDATE -> updateNote();
case QUIT -> System.out.println("Good bye.");
default -> System.out.println("Invalid: " + choice);
}
}
else {
System.out.println("No selection entered. Retry.");
}
}
}
public static void main(String[] args) {
try {
FileSys fs = new FileSys();
fs.showMenu();
}
catch (IOException xIo) {
xIo.printStackTrace();
}
}
}
Your code does not initially load memory with contents of file notes.txt so I added that in the constructor. Consequently you don't need to append to the file since you simply overwrite it with contents of memory.
The file handling is done using NIO.2 including try-with-resources – which was added in Java 7. There are more NIO.2 examples in the JDK documentation.
Whenever the code throws an unexpected exception, it is nearly always a good idea to print the stack trace.

While loop not working accordingly

The following code asks the user to input the description, price and quantity of item he consumed.
There is a while loop to ask if he wants to input more items! If he does, the program ask to insert another description, price and quantity of the other items, and so on.
If he doesn't want to input more items, the output is all the items he added to the array, and the total of the bill.
Problem is: the first time the while runs, it works, but on the second time if the user answer with "y", it returns an error, as if he jumped from the description right to the price of the second item. If the user type the description, then it gets an input mismatch exception.
Main Class:
package com.company;
import java.util.ArrayList;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
ArrayList<Gastos> billArr = new ArrayList<>();
Scanner input = new Scanner(System.in);
int qntItems = 0 , counter = 0;
String ans;
Gastos bill = new Gastos();
while (qntItems == 0) {
System.out.print("Want to input another item? Y/N: ");
ans = input.nextLine();
switch (ans){
case "y":
qntItems = 0;
bill.setDescription();
bill.setPrice();
bill.setQuantity();
bill.getTotal();
billArr.add(bill);
counter = counter + 1;
break;
case "n": qntItems = 1;
break;
default: System.out.print("Invalid!");
System.out.println();
break;
}
input.close();
}
for (int i = 0; i < billArr.size();i++){
System.out.print(bill.getDescription() + ", " + bill.getPrice() + ", " + bill.getQuantity() + ", " + "the total is: " + bill.getTotal());
}
}
}
and the Gastos class:
package com.company;
import java.util.Scanner;
public class Gastos {
private String description;
private double price, quantity, total;
private Scanner input = new Scanner(System.in);
public void setDescription(){
System.out.print("Insert the item name: ");
description = input.nextLine();
}
public void setPrice(){
System.out.print("insert the item price: ");
price = input.nextDouble();
}
public void setQuantity(){
System.out.print("Insert the quantity: ");
quantity = input.nextDouble();
}
public String getDescription(){
return description;
}
public double getPrice() {
return price;
}
public double getQuantity() {
return quantity;
}
public double getTotal(){
total = price * quantity;
return total;
}
}
How can I handle this error?

You have a bug in your 2nd loop.
It should be:
System.out.print(billArr.get(i).getDescription().....
or simply put:
for(Gastos b : billArr){
System.out.print(b.getDescription())
}
Update 1: Another error is you close the Scanner at the end of the first loop. Move input.close(); outside the loop or inside case "n".
Update 2: You have another problem, you need to reinitialize Gastos every time you enter new details about it. So you need to do Gastos bill = new Gastos(); right after case "y": and remove it from where you initialize it before the while loop. Your main should look like this:
public static void main(String[] args) {
ArrayList<Gastos> billArr = new ArrayList<>();
Scanner input = new Scanner(System.in);
int qntItems = 0 , counter = 0;
String ans;
while (qntItems == 0) {
System.out.print("Want to input another item? Y/N: ");
ans = input.nextLine();
switch (ans){
case "y":
Gastos bill = new Gastos();
qntItems = 0;
bill.setDescription();
bill.setPrice();
bill.setQuantity();
bill.getTotal();
billArr.add(bill);
counter = counter + 1;
break;
case "n": qntItems = 1;
input.close();
break;
default: System.out.print("Invalid!");
System.out.println();
break;
}
}
for (Gastos bill : billArr){
System.out.print(bill.getDescription() + ", " + bill.getPrice() + ", " + bill.getQuantity() + ", " + "the total is: " + bill.getTotal());
}
}
I think you need to spend sometime debugging and understanding how java's objects work. These are basic errors which should be easily caught.

InputMismatchError after implementing boolean

I've implemented a boolean to a kennel system I'm developing in Java and I'm getting an InputMismatchError when loading the data from the file.
I've read through a few times and tried to work it out but the solutions I'm trying aren't working. So far I've:
restructured the read in method (initialise) to read the data in properly and in the correct order, then assign it the newPet (local variable) in the correct order.
I then read through the .txt file (below) and made sure everything corresponded the the correct data, strings are being read as strings, ints as ints etc and that hasn't helped.
Can anybody spot the problem that's through the InputMismatch here?
Here is the error:
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextBoolean(Unknown Source)
at KennelDemo.initialise(KennelDemo.java:79)
at KennelDemo.main(KennelDemo.java:337)
with line 79 and 337 being:
boolean mutualBoolean = infile.nextBoolean(); //and
demo.initialise();
Main class (apologises for the length)
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;
public class KennelDemo {
private String filename; // holds the name of the file
private Kennel kennel; // holds the kennel
private Scanner scan; // so we can read from keyboard
private String tempFileName;
private String dogsFile = "dogs.txt";
private String catsFile = "cats.txt";
/*
* Notice how we can make this private, since we only call from main which
* is in this class. We don't want this class to be used by any other class.
*/
private KennelDemo() {
scan = new Scanner(System.in);
boolean fileCorrect = false;
do {
System.out.print("Which animal are you looking to check into the kennel?: " + "\n");
System.out.println("Dog");
System.out.println("Cat");
tempFileName = scan.next();
if(tempFileName.toLowerCase().equals("dog") || tempFileName.toLowerCase().equals("cat")) {
filename = tempFileName.toLowerCase().equals("dog") ? dogsFile : catsFile;
fileCorrect = true;
}
else {
System.out.println("That is not a valid filename, please enter either 'Dog' or 'cat' in lowercase.");
}
}
while(!fileCorrect);
}
/*
* initialise() method runs from the main and reads from a file
*/
private void initialise() {
kennel = new Kennel();
System.out.println("Using file " + filename);
// Using try-with-resource (see my slides from session 15)
try(FileReader fr = new FileReader(filename);
BufferedReader br = new BufferedReader(fr);
Scanner infile = new Scanner(br)){
String kennelName = infile.nextLine();
int kennelSize = infile.nextInt();
infile.nextLine();
kennel.setCapacity(kennelSize);
int numPets = infile.nextInt();
infile.nextLine();
kennel.setName(kennelName);
for(int i=0; i < numPets; i++){
String PetName = infile.nextLine();
int numOwners = infile.nextInt();
infile.nextLine();
ArrayList<Owner> owners = new ArrayList<>();
for(int oCount=0; oCount < numOwners; oCount++){
String name = infile.nextLine();
String phone = infile.nextLine();
Owner owner = new Owner(name, phone);
owners.add(owner);
}
boolean mutualBoolean = infile.nextBoolean();
infile.nextLine();
String favFood = infile.nextLine();
infile.nextLine();
int feedsPerDay = infile.nextInt();
Pet Pet = new Pet(PetName, owners, mutualBoolean, favFood, feedsPerDay);
kennel.addPet(Pet);
}
} catch (FileNotFoundException e) {
System.err.println("The file: " + " does not exist. Assuming first use and an empty file." +
" If this is not the first use then have you accidentally deleted the file?");
} catch (IOException e) {
System.err.println("An unexpected error occurred when trying to open the file " + filename);
System.err.println(e.getMessage());
}
}
/*
* runMenu() method runs from the main and allows entry of data etc
*/
private void runMenu() {
String response;
do {
printMenu();
System.out.println("What would you like to do:");
scan = new Scanner(System.in);
response = scan.nextLine().toUpperCase();
switch (response) {
case "1":
admitPet();
break;
case "2":
changeKennelName();
break;
case "3":
printPetsWithBones();
break;
case "4":
searchForPet();
break;
case "5":
removePet();
break;
case "6":
setKennelCapacity();
break;
case "7":
printAll();
break;
case "Q":
break;
default:
System.out.println("Try again");
}
} while (!(response.equals("Q")));
}
private void setKennelCapacity() {
// set the boolean to check if the user REALLY wants to change the kennel size. We can never be too careful.
// boolean doContinue = false;
// Turns out the boolean does nothing, go figure.
// Still the error check works perfectly, now just a case of losing the temporary data if the program isn't closed through the menu.
// Kennel currently doesn't save until you use "q" at the menu to save the information. Possible solutions?
// Hello? Is this thing on?
int currentKennelCapacity = kennel.getCapacity();
System.out.println("The current kennel holds " + currentKennelCapacity + ", are you sure you want to change the current kennel size?");
String userWantsToContinue;
userWantsToContinue = scan.nextLine().toUpperCase();
if(userWantsToContinue.equals("Y")){
// doContinue = true;
System.out.print("Please enter the new size of the kennel you'd like: ");
int max = scan.nextInt();
scan.nextLine();
kennel.setCapacity(max);
System.out.println("The new kennel size is " + max + ", we'll now return you to the main menu. Please make sure the quit the program at the end of your session to save any changes. \n");
}
else System.out.println("No problem, we'll return you back to the main menu. \n");
//Duplicate code that caused an error when running through the conditions above, saved in case of future reference.
/* System.out.print("Enter max number of Pets: ");
int max = scan.nextInt();
scan.nextLine();
kennel.setCapacity(max);
*/
}
private void printPetsWithBones() {
Pet[] PetsWithBones = kennel.obtainDogsWhoLikeBones();
System.out.println("Pets with bones: ");
for (Pet d: PetsWithBones){
System.out.println("Pet name: " + d.getName());
}
}
/*
* printAll() method runs from the main and prints status
*/
private void printAll() {
Pet[] allPets = kennel.displayAllPets();
for (Pet p: allPets){
System.out.println("Animal name: " + p.getName());
System.out.println("Original owner(s): " + p.getOriginalOwners());
if(filename.equals(dogsFile)){
System.out.println("Do they like bones? " + Dog.getLikesBones());
}
else if(filename.equals(catsFile)){
System.out.println("Can they share a run? " + Cat.getShareRun());
}
System.out.println("Favourite food: " + p.getFavouriteFood());
System.out.println("Feeds per day: " + p.getFeedsPerDay());
System.out.println("====================================");
}
}
/*
* save() method runs from the main and writes back to file
*/
private void save() {
try(FileWriter fw = new FileWriter(filename);
BufferedWriter bw = new BufferedWriter(fw);
PrintWriter outfile = new PrintWriter(bw);){
outfile.println(kennel.getName());
outfile.println(kennel.getCapacity());
outfile.println(kennel.getNumOfPets());
Pet[] Pets = kennel.obtainAllPets();
for (Pet d: Pets){
outfile.println(d.getName());
Owner[] owners = d.getOriginalOwners();
outfile.println(owners.length);
for(Owner o: owners){
outfile.println(o.getName());
outfile.println(o.getPhone());
}
// TODO outfile.println(d.getLikesBones());
outfile.println(d.getFeedsPerDay());
outfile.println(d.getFavouriteFood());
}
} catch (IOException e) {
System.err.println("Problem when trying to write to file: " + filename);
}
}
private void removePet() {
System.out.println("which Pet do you want to remove");
String Pettoberemoved;
Pettoberemoved = scan.nextLine();
kennel.removePet(Pettoberemoved);
}
private void searchForPet() {
String allNames = kennel.getName();
System.out.println("Current pet in the kennel: " + allNames + "\n");
System.out.println("Which pet would you like to get the details for?");
String name = scan.nextLine();
Pet Pet = kennel.search(name);
if (Pet != null){
System.out.println(Pet.toString());
} else {
System.out.println("Could not find Pet: " + name);
}
}
private void changeKennelName() {
String name = scan.nextLine();
kennel.setName(name);
}
private void admitPet() {
boolean mutualBoolean = false;
if(filename.equals(dogsFile)){
System.out.println("enter on separate lines: name, owner-name, owner-phone, do they like bones?, favourite food, number of times fed");
}
else if(filename.equals(catsFile)){
System.out.println("enter on separate lines: name, owner-name, owner-phone, can they share a run?, favourite food, number of times fed");
}
String name = scan.nextLine();
ArrayList<Owner> owners = getOwners();
if(filename.equals(dogsFile)){
System.out.println("Does he like bones? (Y/N)");
}
else if(filename.equalsIgnoreCase(catsFile)){
System.out.println("Can the cat share a run? (Y/N)");
}
String booleanCheck;
booleanCheck = scan.nextLine().toUpperCase();
if (booleanCheck.equals("Y")) {
mutualBoolean = true;
}
System.out.println("What is his/her favourite food?");
String fav;
fav = scan.nextLine();
System.out.println("How many times is he/she fed a day? (as a number)");
int numTimes;
numTimes = scan.nextInt(); // This can be improved (InputMismatchException?)
numTimes = scan.nextInt();
Pet newPet = new Pet(name, owners, mutualBoolean, fav, numTimes);
kennel.addPet(newPet);
System.out.println("Pet " + newPet.getName() + " saved.");
// Save when you add new Pet in case the program isn't closed via the correct menu.
// Everything will still save when case "q" is used though.
save();
}
private ArrayList<Owner> getOwners() {
ArrayList<Owner> owners = new ArrayList<Owner>();
String answer;
do {
System.out
.println("Enter on separate lines: owner-name owner-phone");
String ownName = scan.nextLine();
String ownPhone = scan.nextLine();
Owner own = new Owner(ownName, ownPhone);
owners.add(own);
System.out.println("Another owner (Y/N)?");
answer = scan.nextLine().toUpperCase();
} while (!answer.equals("N"));
return owners;
}
private void printMenu() {
if(filename.equals(catsFile)) {
System.out.println("1 - add a new cat ");
System.out.println("2 - set up Kennel name");
System.out.println("4 - search for a cat");
System.out.println("5 - remove a cat");
System.out.println("6 - set kennel capacity");
System.out.println("7 - print all cats");
System.out.println("q - Quit");
}
else if(filename.equals(dogsFile)) {
System.out.println("1 - add a new dog ");
System.out.println("2 - set up Kennel name");
System.out.println("3 - print all dogs who like bones");
System.out.println("4 - search for a dog");
System.out.println("5 - remove a dog");
System.out.println("6 - set kennel capacity");
System.out.println("7 - print all dogs");
System.out.println("q - Quit");
}
}
// /////////////////////////////////////////////////
public static void main(String args[]) {
System.out.println("**********HELLO***********");
KennelDemo demo = new KennelDemo();
demo.initialise();
demo.runMenu();
demo.printAll();
demo.save();
System.out.println("***********GOODBYE**********");
}
}
and here is the .txt file being read from:
DogsRUs // kennel name
20 // capacity
3 // number of pets
Rover //pet name
2 // number of owners
Chris Loftus // first owner
1234 // phone number
Pete Hoskins // second owner
2222 // phone number
1 // boolean for mutualBoolean
biscuits // favourite food
// NOTE: for some reason favFood wasn't being added but it wasn't causing an error at all, it's the boolean that's throwing the input error. Structure above repeats for the data below.
Dinky
1
James Bond
007007
1
Gold fingers
catTest
1
Billy
456789
1
Curry
Clearly the problem is the boolean being read in but I really can't see the solution to it at all unfortunately. When mutualBoolean was likeBones (originally the program was only being used to check dogs in rather than dogs and cats) it was working fine.
Here is the code I've used to inherit for the mutualBoolean that's being used
import java.util.ArrayList;
public class Pet {
protected ArrayList<Owner> originalOwners;
protected boolean mutualBoolean;
protected String petName;
protected String favFood;
protected int foodPerDay;
public Pet(String name, ArrayList<Owner> owners, boolean mutualBoolean, String food, int mealsPerDay) {
petName = name;
this.favFood = food;
this.foodPerDay = mealsPerDay;
originalOwners = new ArrayList<Owner>();
for(Owner o: owners){
Owner copy = new Owner(o.getName(), o.getPhone());
originalOwners.add(copy);
}
this.mutualBoolean = mutualBoolean;
}
public String getName() {
return petName;
}
public void setName(String newName) {
petName = newName;
}
/*protected boolean mutualBoolean() {
return mutualBoolean;
}*/
/**
* Returns a copy of the original owners
* #return A copy of the original owners as an array
*/
public Owner[] getOriginalOwners(){
Owner[] result = new Owner[originalOwners.size()];
result = originalOwners.toArray(result);
return result;
}
/**
* How many times a day to feed the dog
* #param feeds The number of feeds per day
*/
public void setFeedsPerDay(int feeds){
foodPerDay = feeds;
}
/**
* The number of feeds per day the dog is fed
* #return The number of feeds per day
*/
public int getFeedsPerDay(){
return foodPerDay;
}
/**
* What's his favourite food?
* #param food The food he likes
*/
public void setFavouriteFood(String food){
favFood = food;
}
/**
* The food the dog likes to eat
* #return The food
*/
public String getFavouriteFood(){
return favFood;
}
/**
* Note that this only compares equality based on a
* dog's name.
* #param The other dog to compare against.
*/
#Override
public boolean equals(Object obj) { // Generated by Eclipse to be more robust
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Dog other = (Dog) obj;
if (petName == null) {
if (other.petName != null)
return false;
} else if (!petName.equals(other.petName))
return false;
return true;
}
/**
* A basic implementation to just return all the data in string form
*/
public String toString() {
return "Dog name:" + petName + "Original Owner:" + originalOwners + "Favfood:" + favFood
+ "FoodPerDay:" + foodPerDay;
}
}
and the Dog class
import java.util.ArrayList;
public class Dog extends Pet {
public static boolean likesBones;
public Dog(String name, ArrayList<Owner> owners, String food, int mealsPerDay, boolean likeBones) {
super(name, owners, likeBones, food, mealsPerDay);
Dog.likesBones = likeBones;
}
/**
* Does the dog like bones?
* #return true if he does
*/
public static boolean getLikesBones() {
return likesBones;
}
}

Comparing an Arraylist to a String

I am trying to compare a string which the user enters in case 3 in the ProcessRecords class. I am then trying to compare that string to each last name in the Arraylist and if a record matches the user's input then i want to print it. I am not sure how to accomplish this but I would appreciate any guidance.
import java.util.*;
import java.io.*;
public class ProcessRecords {
public static void AskUser()
throws Exception {
Scanner preference = new Scanner(System.in);
//Creating a new scanner will allow us to gather user input
boolean flag=true;
//I will use this for my while loop
while (flag) {
System.out.println("What type of Search would you like to run?\n 1)Search for all students\n 2) Search for students graduating in a specific year\n 3)Search for students whose last name begins with a certain string\n(4) Exit\n");
int searchType=preference.nextInt();
//This variable will store what type of query the user would like to run
switch(searchType) {
case 1:
System.out.println("Gathering Records for all students\n");
//Query.getAll();
break;
//Call Query Method in the Query Class to return all students in the colletion
case 2: System.out.println("What graduation year would you like to search for? \n");
int yearsearch=preference.nextInt();
Query.getYears(yearsearch);
break;
//Call Query Method to return students who are graduating in the specified year
//Pass the "yearsearch" variable to the Query class
case 3:
System.out.println("What string would you like to search for? \n");
String lstsearch=preference.next();
Query.getLast(lstsearch);
break;
case 4:
System.out.println("You have chosen to exit the program. Thank you!");
flag=false;
break;
default:
System.out.println("Please pick a number between 1 and 4") ;
break;
//Call Query Method in the Query Class to return students who have the string in their last name
//Also I need to pass the "lstsearch" variable to the Query class to search through last names
}
}
}
public List<StudentRecord> studentRecords;
public static void main(String[] args)
throws Exception
{
Scanner input = new Scanner(new File("students.txt"));
//This will import the file
input.nextLine();
//This will skip the headers in the file
System.out.println("Processing file now...");
//Let the user know that the file is being processed
int id;
String last;
String first;
int year;
int i=1;
// Declare variables that we will extract from the file
//Now we will being processing the file with a while loop
List<StudentRecord> studentRecords = new ArrayList<StudentRecord>();
while(input.hasNext())
{
id=input.nextInt();
last=input.next();
first=input.next();
year=input.nextInt();
StudentRecord record = new StudentRecord(id, last, first, year);
studentRecords.add(record);
System.out.println(id + " " + last + " " + first + " " + year + "\n");
}
System.out.println(" You have successfully read and printed from the file!");
for (StudentRecord s : studentRecords)
System.out.println(s.toString());
Query query = new Query(studentRecords);
}
}
+++++++++++++++++++++++++++++++++++
Next Class
import java.util.*;
public class StudentRecord
{
private int id;
private String last;
private String first;
private int year;
public StudentRecord(int id, String last, String first, int year)
{
this.id=id;
this.last=last;
this.first=first;
this.year=year;
}
public String toString()
{
return id + " " + last + " " + first + " " + year;
}
public int getYear()
{
return year;
}
public String getLast()
{
return last;
}
}
+++++++++++++++++++++++++++++++++++
Next Class
import java.util.*;
import java.io.*;
public class Query
{
static List<StudentRecord> records;
public List<StudentRecord> studentRecords;
public Query(List<StudentRecord> records) {
this.records = records;
}
public static void getYears(int yearSearch) {
//I am trying to create a method to get students who are graduating in a specific year.
// I want to call this method in the ProcessRecord SwitchCase Case #2
int count = 0;
System.out.println("ID" +" " +"Last" + " " + "First" + " " + "Year \n");
for(StudentRecord record : records) {
if(record.getYear() == yearSearch) {
System.out.println((record.toString()));
count++;
}
System.out.printf("\n");
}
}
public static void getLast(String lstsearch){
int count =0;
System.out.println("ID" +" " +"Last" + " " + "First" + " " + "Year \n");
int sizes= lstsearch.length();
System.out.println(lstsearch);
for(StudentRecord record : records) {
System.out.println(count);
if(record.getLast() == lstsearch) {
System.out.println((record.toString()));
count++;
}
}
}
public void getAll(){
for (StudentRecord s : studentRecords)
System.out.println(s.toString());
}
}
Once again, I am looking for help searching through the arraylist and if the last name in the array list starts with the string,i.e."g", then I want to print it. Thank you for all of your help!

public static StudentRecord searchRecords(Collection<StudentRecord> records, String lastName)
{
for (StudentRecord record : records)
{
if (lastName.equalsIgnoreCase(record.getLast()))
return record;
}
return null;
}
This will search through your array for the appropriate record. If it exists it returns that record -- otherwise it returns null. If you have such questions in the future you can always consult the appropriate javadoc for some methods you can use to compare objects.

I need to restructure this class without the use of instance variables

So I'm doing a TUI and this was my first iteration.
package bulb.classes;
import java.util.Scanner;
import java.util.ArrayList;
public class RoomTUI {
private ArrayList<Room> rooms;
Scanner scan = new Scanner (System.in);
private int userNumber;
private String userAnswer;
public void run() {
rooms = new ArrayList<Room>();
introduction();
userNumber = 0;
options();
while(userNumber < 5) {
if(userNumber == 1) {
newRoom();
}
if(userNumber == 2) {
addBulbToRoom();
}
if(userNumber == 3) {
clickAllBulbsInRoom();
}
if(userNumber == 4) {
printDescriptionOfBulbs();
}
}
System.out.println("Goodbye");
}
public int getUserInt(String aString) {
System.out.println(aString);
userAnswer = scan.nextLine();
userNumber = Integer.parseInt(userAnswer);
return userNumber;
}
public void displayRooms() {
System.out.println("Possible rooms to choose from.");
String tempString = "";
int roomIndex = 0;
for (int i = 0; i < rooms.size(); i++) {
tempString = tempString + "Room " + roomIndex++ + ": " + rooms.get(i).getDescription() + "\n";
}
System.out.println(tempString);
}
public void introduction() {
System.out.println("Welcome! With this program you can make rooms and design and place the light bulbs for each room you create.");
}
public void options() {
System.out.println("1 : Create a new Room");
System.out.println("2 : Add a bulb to an existing room");
System.out.println("3 : Click all of the bulbs in a particular room");
System.out.println("4 : Display a description of all bulbs in a particular room");
System.out.println("5 : Quit");
getUserInt("What would you like to do?");
}
public void newRoom() {
System.out.println("Please enter a name for your room");
String name = scan.nextLine();
Room aRoom = new Room(name);
rooms.add(aRoom);
System.out.println("You have added the " + name + ".");
options();
}
public void addBulbToRoom() {
displayRooms();
System.out.println("Which room do you want the bulb in?");
String choice = scan.nextLine();
int choiceNumber = Integer.parseInt(choice);
System.out.println("Please enter the blub's color.");
String color = scan.nextLine();
System.out.println("Please enter the blub's increment amount.");
String incrementS = scan.nextLine();
int incrementI = Integer.parseInt(incrementS);
ThreeWayBulb aBulb = new ThreeWayBulb(color, incrementI);
rooms.get(choiceNumber).addBulb(aBulb);
System.out.println("A " + color + " bulb with and increment of " + incrementI + " was added.");
options();
}
public void clickAllBulbsInRoom() {
displayRooms();
System.out.println("Which room do you want the bulbs clicked?");
String choice = scan.nextLine();
int choiceNumber = Integer.parseInt(choice);
rooms.get(choiceNumber).clickAllBulbs();
System.out.println("The bulbs in " + rooms.get(choiceNumber).getDescription() + " have been clicked.");
options();
}
public void printDescriptionOfBulbs() {
displayRooms();
System.out.println("Please enter a room number.");
String choice = scan.nextLine();
int choiceNumber = Integer.parseInt(choice);
System.out.println(rooms.get(choiceNumber).getDescription() + " with " + rooms.get(choiceNumber).returnSize() + " bulbs: " + "\n" + rooms.get(choiceNumber).toString());
options();
}
}
My instructor wants me to do this without instance variables He said if a method needs the ArrayList that I should make it a parameter and have no instance variables in my TUI. I can't for the life of me figure out how to do that. Also, making it static work fly either. Thanks for any help you can give.

He wants you to declare the ArrayList from a central location (such as the main thread) and then pass it as an argument to the functions that use it. This way if you were to take methods and put them in different classes then it wouldn't break because they're not dependent on this class.
For example if we take your newRoom class:
public void newRoom(List<Room> roomList) {
System.out.println("Please enter a name for your room");
String name = scan.nextLine();
Room aRoom = new Room(name);
roomList.add(aRoom);
System.out.println("You have added the " + name + ".");
options();
}
EDIT: The easiest way to achieve this is to probably move the declaration of rooms to within your run method. Now for each location in the code that reports "unknown variable rooms" you can modify the function to take an ArrayList as a parameter.

Well, eliminating userNumber and userAnswer as members is trivial; their usage is very localized.
For the list, just pass it around after creating it in your main loop.
The scanner is used multiple places; it could also be passed around, I suppose.