Java inheritence and arraylist to sort [closed] - java

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Hey i have a project in which by using inheritence and arraylist i have to take input from file and then show the output after sorting them year wise but in my code my array list's are empty and i am not able to figure out how to solve it.
import java.io.FileNotFoundException;
public class Main {
public static void main(String[] args) throws FileNotFoundException {
// TODO Auto-generated method stub
Driver driver = new Driver();
driver.start();
}
}
import java.util.ArrayList;
import java.util.Scanner;
import javax.swing.JOptionPane;
import java.io.*;
public class Driver {
public void start() throws FileNotFoundException{
// Initialize arraylists
ArrayList<Movie> adventure = new ArrayList<>();
ArrayList<Movie> drama = new ArrayList<>();
ArrayList<Movie> fantasy = new ArrayList<>();
ArrayList<Movie> romance = new ArrayList<>();
ArrayList<Movie> sciFi = new ArrayList<>();
ArrayList<Movie> thriller = new ArrayList<>();
ArrayList<Movie> war = new ArrayList<>();
File myObj = new File("MovieListing.txt");
Scanner myReader = new Scanner(myObj);
String directorName = myReader.nextLine();
String composerName = myReader.nextLine();
while(myReader.hasNextLine()) {
String movie = myReader.nextLine();
String[] movieInfo = movie.split(",");
String title = movieInfo[0];
int year = Integer.parseInt(movieInfo[1]);
String genre = movieInfo[2];
String rating = movieInfo[3];
Movie movie1 = new Movie(title,year,genre,rating,directorName,composerName);
//sort movies into arraylists
if (genre.equals("Adventure"))
{
adventure.add(movie1);
}
else if (genre.equals("Drama"))
{
drama.add(movie1);
}
else if (genre.equals("Fantasy"))
{
fantasy.add(movie1);
}
else if (genre.equals("Romance"))
{
romance.add(movie1);
}
else if (genre.equals("Sci Fi"))
{
sciFi.add(movie1);
}
else if (genre.equals("Thriller"))
{
thriller.add(movie1);
}
else if (genre.equals("War"))
{
war.add(movie1);
}
}
myReader.close();
System.out.print(adventure);
for(Movie movie:war) {
System.out.print(movie.getTitle());
}
// Ask the user which genre they would like to view
String genre = JOptionPane.showInputDialog("Director: " +directorName + "\n" +
"Composer: " + composerName + "\n" +
"Which genre would you like? \n" +
"1. Adventure \n" +
"2. Drama \n" +
"3. Fantasy \n" +
"4. Romance \n" +
"5. SciFi \n" +
"6. Thriller \n" +
"7. War \n" +
"Your choice: ");
// Sort the movies by year released
adventure.sort(new MovieComparator());
drama.sort(new MovieComparator());
fantasy.sort(new MovieComparator());
romance.sort(new MovieComparator());
sciFi.sort(new MovieComparator());
thriller.sort(new MovieComparator());
war.sort(new MovieComparator());
// Display the output dialog box
String output = "Director: " +directorName + "\n" +
"Composer: " +composerName + "\n" +
"Genre: " + genre + "\n" +
"Movie Title\tYear Released\tRating\n";
if (genre.equals("1")) {
for (Movie movie : adventure) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
else if (genre.equals("2")) {
for (Movie movie : drama) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
else if (genre.equals("3")) {
for (Movie movie : fantasy) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
else if (genre.equals("4")) {
for (Movie movie : romance) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
else if (genre.equals("5")) {
for (Movie movie : sciFi) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
else if (genre.equals("6")) {
for (Movie movie : thriller) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
else if (genre.equals("7")) {
for (Movie movie : war) {
output += movie.getTitle() + "\t\t" + movie.getYearReleased() + "\t\t" + movie.getRating() + "\n";
}
}
JOptionPane.showMessageDialog(null, output);
}
}
public class Movie extends Director {
private String title;
private int yearReleased;
private String genre;
private String rating;
public Movie(String title, int yearReleased, String genre, String rating, String directorName, String composerName) {
super(directorName, composerName);
this.title = title;
this.yearReleased = yearReleased;
this.genre = genre;
this.rating = rating;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public int getYearReleased() {
return yearReleased;
}
public void setYearReleased(int yearReleased) {
this.yearReleased = yearReleased;
}
public String getGenre() {
return genre;
}
public void setGenre(String genre) {
this.genre = genre;
}
public String getRating() {
return rating;
}
public void setRating(String rating) {
this.rating = rating;
}
}
public class Director {
private String directorName;
private String composerName;
public Director(String d, String c) {
this.directorName = d;
this.composerName = c;
}
public String getDirectorName() {
return directorName;
}
public void setDirectorName(String directorName) {
this.directorName = directorName;
}
public String getComposerName() {
return composerName;
}
public void setComposerName(String composerName) {
this.composerName = composerName;
}
}
This is the link for the file that needs to be useed in the code https://drive.google.com/file/d/1FkDSAlEv3waby-ML1dKPf3Ouk3S7O99O/view?usp=sharing
Ecpected output format:-
Director: Steven Spielberg
Composer: John Williams
Genre: Drama
Movie Title Year Released Rating
Amistad 1997 R
The Post 2017 PG-13
....

Running your code without any changes throwed an exception:
java.lang.NumberFormatException: For input string: " 1994"
The exception was reported to be caused by this statement in class Driver:
int year = Integer.parseInt(movieInfo[1]);
The reason is quite obvious: There is a leading space infront of 1994, that's why it is throwing that exception. The reason why there is a space infront of 1994 lies within the input file:
Schindler's List, 1994, War, R
The same applies for the "genre" column in the input file and that's the reason why none of the imported movies is associated to the pre-defined genres during import:
if (genre.equals("War")) {
" War" (from import) is different from "War".
You need to remove leading (and trailing) spaces during import. You could do this calling java.lang.String#trim() on item of array movieInfo or by using an appropriate regular expression whith java.lang.String#split(String):
String[] movieInfo = movie.split(",\\s*");
This will split the input line at every occurence of "comma, followed optionally by spaces", effectively removing leading spaces from the imported fields.

Related

Java vanClass giving cannot find symbol error [closed]

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 2 years ago.
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I have code that has several classes with different cars and some classes. Below is my code, I'm not sure why vanClass van; is not working as it is basically a copy paste of the past classes that work. Any help is appreciated. To clarify, I am only having problems with the last few lines of the autopark class where I initiate vanClass as van and go from there.
import java.util.*;
class sedan {
String make;
String model;
String color;
int year;
double price;
boolean fourWD;
boolean isheavyDuty;
String carries;
public sedan(String initMake, String initModel, String initColor, int initYear, double initPrice) {
make = initMake;
model = initModel;
color = initColor;
year = initYear;
price = initPrice;
}
#Override
public String toString() {
String name = "Sedan";
String main = (color + " " + make + " " + model + " " + name + " (" + year + ") costs $" + price);
return main;
}
}
class SUV {
String make;
String model;
String color;
int year;
double price;
boolean fourWD;
String carries;
public SUV(String initMake, String initModel, String initColor, int initYear, double initPrice, boolean initFourWD){
make = initMake;
model = initModel;
color = initColor;
year = initYear;
price = initPrice;
fourWD = initFourWD;
}
public String toString() {
String name = "SUV";
String main = new String();
if (fourWD) {
main = ("4WD " + color + " " + make + " " + model + " " + name + " (" + year + ") costs $" + price);
}
else {
main = (color + " " + make + " " + model + " " + name + " (" + year + ") costs $" + price);
}
return main;
}
}
class truckClass {
String make;
String model;
String color;
int year;
double price;
boolean fourWD;
boolean isheavyDuty;
String carries;
public truckClass(String initMake, String initModel, int initYear, double initPrice, boolean initisheavyDuty, String initCarries){
make = initMake;
model = initModel;
year = initYear;
price = initPrice;
isheavyDuty = initisheavyDuty;
carries = initCarries;
}
public String toString() {
String name = "Truck";
String main = (make + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price);
return main;
}
class vanClass {
String make;
String model;
int year;
double price;
boolean isCovered;
String carries;
public vanClass(String initMake, String initModel, int initYear, double initPrice, boolean initisCovered, String initCarries){
make = initMake;
model = initModel;
year = initYear;
price = initPrice;
isCovered = initisCovered;
carries = initCarries;
}
public String toString() {
String name;
String main;
if (isCovered()){
name = "covered Van";
String main = (make + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price);
}
else {
name = "Van";
String main = (make + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price);
}
return main;
}
}
public class autoPark {
public static void main(String args[]) {
sedan sedan1; // declaring cars object by name sedan1
sedan1 = new sedan("Ford" , "Model-1" , "white" , 2015, 20000); // initialising sedan1 using sedan constructor
System.out.println(sedan1); // printing sedan1 for invoking toString() method
SUV suv; // declaring cars object by name suv
suv = new SUV("Ford" , "Model-1" , "white" , 2015, 20000, true); // initialising suv using SUV constructor
System.out.println(suv); // printing suv for invoking toString() method
truckClass truck; //declaring cars object by name truck
truck = new truckClass("Ford" , "Model-1" , 2015, 20000, true, "2"); // initialising truck using truck constructor
System.out.println(truck); // printing truck for invoking toString() method
vanClass van;
van = new vanClass("Ford" , "Model-1" , 2015, 20000, true, "2";
System.out.println(van);
}
}
I came across 4 issues
missing } just before starting vanClass
missing ) after van = new vanClass("Ford" , "Model-1" , 2015, 20000, true, "2");
extra pair of parenthesis after isCovered which is a member data instead of method
Declaring main as String twice inside the toString method of SUV class
import java.util.*;
class sedan {
String make;
String model;
String color;
int year;
double price;
boolean fourWD;
boolean isheavyDuty;
String carries;
public sedan(String initMake, String initModel, String initColor, int initYear, double initPrice) {
make = initMake;
model = initModel;
color = initColor;
year = initYear;
price = initPrice;
}
#Override
public String toString() {
String name = "Sedan";
String main = (color + " " + make + " " + model + " " + name + " (" + year + ") costs $" + price);
return main;
}
}
class SUV {
String make;
String model;
String color;
int year;
double price;
boolean fourWD;
String carries;
public SUV(String initMake, String initModel, String initColor, int initYear, double initPrice, boolean initFourWD){
make = initMake;
model = initModel;
color = initColor;
year = initYear;
price = initPrice;
fourWD = initFourWD;
}
public String toString() {
String name = "SUV";
String main = new String();
if (fourWD) {
main = ("4WD " + color + " " + make + " " + model + " " + name + " (" + year + ") costs $" + price);
}
else {
main = (color + " " + make + " " + model + " " + name + " (" + year + ") costs $" + price);
}
return main;
}
}
class truckClass {
String make;
String model;
String color;
int year;
double price;
boolean fourWD;
boolean isheavyDuty;
String carries;
public truckClass(String initMake, String initModel, int initYear, double initPrice, boolean initisheavyDuty, String initCarries){
make = initMake;
model = initModel;
year = initYear;
price = initPrice;
isheavyDuty = initisheavyDuty;
carries = initCarries;
}
public String toString() {
String name = "Truck";
String main = (make + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price);
return main;
}
}
class vanClass {
String make;
String model;
int year;
double price;
boolean isCovered;
String carries;
public vanClass(String initMake, String initModel, int initYear, double initPrice, boolean initisCovered, String initCarries){
make = initMake;
model = initModel;
year = initYear;
price = initPrice;
isCovered = initisCovered;
carries = initCarries;
}
public String toString() {
String name;
String main;
if (isCovered){
name = "covered Van";
main = (make + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price);
}
else {
name = "Van";
main = (make + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price);
}
return main;
}
}
public class autoPark {
public static void main(String args[]) {
sedan sedan1; // declaring cars object by name sedan1
sedan1 = new sedan("Ford" , "Model-1" , "white" , 2015, 20000); // initialising sedan1 using sedan constructor
System.out.println(sedan1); // printing sedan1 for invoking toString() method
SUV suv; // declaring cars object by name suv
suv = new SUV("Ford" , "Model-1" , "white" , 2015, 20000, true); // initialising suv using SUV constructor
System.out.println(suv); // printing suv for invoking toString() method
truckClass truck; // declaring cars object by name truck
truck = new truckClass("Ford" , "Model-1" , 2015, 20000, true, "2"); // initialising truck using truck constructor
System.out.println(truck); // printing truck for invoking toString() method
vanClass van;
van = new vanClass("Ford" , "Model-1" , 2015, 20000, true, "2");
System.out.println(van);
}
}
You need to consider using inheritance as mentioned by others.
I fixed and refactored your class using inheritance:
abstract class Vehicle{
protected String maker;
protected String model;
protected int year;
protected double price;
public Vehicle(String maker, String model, int year, double price) {
this.maker=maker;
this.model=model;
this.year=year;
this.price=price;
}
abstract String getType();
#Override
public String toString() {
return maker + " " + model + " " + getType() + " (" + year + ") costs $" + price;
}
}
abstract class HeavyVehicle extends Vehicle{
protected String carries;
public HeavyVehicle(String maker, String model, int year, double price, String carries) {
super(maker, model, year, price);
this.carries=carries;
}
}
class SUV extends HeavyVehicle{
String color;
boolean fourWD;
public SUV(String maker, String model, String initColor, int year, double price,
boolean initFourWD) {
super(maker,model,year,price,"1");
color = initColor;
fourWD = initFourWD;
}
public String toString() {
StringBuilder sb = new StringBuilder();
if (fourWD) {
sb.append("4WD ");
}
sb.append(color + " " + super.toString());
return sb.toString();
}
#Override
String getType() {
return "SUV";
}
}
class Truck extends HeavyVehicle{
public Truck(String maker, String model, int year, double price,String carries) {
super(maker,model,year,price,carries);
}
public String toString() {
return maker + " " + model + " " + getType() + " (" + year + ") carries" + carries + " costs $" + price;
}
#Override
String getType() {
return "Truck";
}
}
class Van extends HeavyVehicle{
boolean isCovered;
public Van(String maker, String model, int year, double price, boolean isCovered, String carries){
super(maker,model,year,price,carries);
this.isCovered = isCovered;
}
public String toString() {
String name = isCovered ? "covered Van" : getType();
return maker + " " + model + " " + name + " (" + year + ") carries" + carries + " costs $" + price;
}
#Override
String getType() {
return "Van";
}
}
class Sedan extends Vehicle{
String color;
public Sedan(String maker, String model, String color, int year, double price) {
super(maker,model,year,price);
this.color = color;
}
#Override
public String toString() {
return color + " " + super.toString();
}
#Override
String getType() {
return "Sedan";
}
}
public class Main {
public static void main(String args[]) {
Sedan sedan1; // declaring cars object by name sedan1
sedan1 = new Sedan("Ford", "Model-1", "white", 2015, 20000); // initialising sedan1 using sedan constructor
System.out.println(sedan1); // printing sedan1 for invoking toString() method
SUV suv; // declaring cars object by name suv
suv = new SUV("Ford", "Model-1", "white", 2015, 20000, true); // initialising suv using SUV constructor
System.out.println(suv); // printing suv for invoking toString() method
Truck truck; // declaring cars object by name truck
truck = new Truck("Ford", "Model-1", 2015, 20000, "2"); // initialising truck using truck constructor
System.out.println(truck); // printing truck for invoking toString() method
Van van;
van = new Van("Ford", "Model-1", 2015, 20000, true, "2");
System.out.println(van);
}
}
Was missing a } and ). Silly mistake

How to Pair Up Random Indices of an ArrayList with each other

I am currently working on a project where I read in a CSV file that contains a list of Pokemon, as well as their traits. I am trying to run a battle simulator that randomly pairs up these Pokemon with each other and compares their combatScore, which is a result of a simple calculation using their traits such as speed, attack, defense, etc. I read in all of the Pokemon from the CSV file into an ArrayList of type Pokemon. Now, I want to randomly pair them up with each other and compare their combatScore; whoever has the higher score moves on to the next round, and the loser is placed into another ArrayList of defeated Pokemon. However, I do not know how to randomly pair up the Pokemon. Here is my code of the main class so far:
import java.io.*;
import java.util.ArrayList;
import java.util.Random;
public class assign1 {
public static void main(String[] args) throws IOException {
String csvFile = args[0]; //path to CSV file
String writeFile = args[1]; //name of output file that contains list of Pokemon and their traits
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
ArrayList<Pokemon> population = new ArrayList<Pokemon>();
FileWriter fileWriter = new FileWriter(writeFile);
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
try {
br = new BufferedReader(new FileReader(csvFile));
String headerLine = br.readLine(); // used to read first line of CSV file that contains headers
while ((line = br.readLine()) != null) {
Pokemon creature = new Pokemon();
// use comma as separator
String[] pokemon = line.split(cvsSplitBy);
creature.setId(pokemon[0]);
creature.setName(pokemon[1]);
creature.setType1(pokemon[2]);
creature.setType2(pokemon[3]);
creature.setTotal(pokemon[4]);
creature.setHp(Integer.parseInt(pokemon[5]));
creature.setAttack(Integer.parseInt(pokemon[6]));
creature.setDefense(Integer.parseInt(pokemon[7]));
creature.setSpAtk(Integer.parseInt(pokemon[8]));
creature.setSpDef(Integer.parseInt(pokemon[9]));
creature.setSpeed(Integer.parseInt(pokemon[10]));
creature.setGeneration(Integer.parseInt(pokemon[11]));
creature.setLegendary(Boolean.parseBoolean(pokemon[12]));
creature.getCombatScore();
// Adds individual Pokemon to the population ArrayList
population.add(creature);
// Writes to pokemon.txt the list of creatures
bufferedWriter.write(creature.getId() + ". "
+ "Name: " + creature.getName() + ": "
+ "Type 1: " + creature.getType1() + ", "
+ "Type 2: " + creature.getType2() + ", "
+ "Total: " + creature.getTotal() + ", "
+ "HP: " + creature.getHp() + ", "
+ "Attack: " + creature.getAttack() + ", "
+ "Defense: " + creature.getDefense() + ", "
+ "Special Attack: " + creature.getSpAtk() + ", "
+ "Special Defense: " + creature.getSpDef() + ", "
+ "Speed: " + creature.getSpeed() + ", "
+ "Generation: " + creature.getGeneration() + ", "
+ "Legendary? " + creature.isLegendary() + ", "
+ "Score: " + creature.getCombatScore());
bufferedWriter.newLine();
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
if (br != null) {
try {
br.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
bufferedWriter.close();
}
}
And here is the code for my Pokemon class:
public class Pokemon {
String id;
String name;
String type1;
String type2;
String total;
int hp;
int attack;
int defense;
int spAtk;
int spDef;
int speed;
int generation;
boolean legendary;
public Pokemon() {}
public String getId () {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getType1() {
return type1;
}
public void setType1(String type1) {
this.type1 = type1;
}
public String getType2() {
return type2;
}
public void setType2(String type2) {
this.type2 = type2;
}
public String getTotal() {
return total;
}
public void setTotal(String total) {
this.total = total;
}
public int getHp() {
return hp;
}
public void setHp(int hp) {
this.hp = hp;
}
public int getAttack() {
return attack;
}
public void setAttack(int attack) {
this.attack = attack;
}
public int getDefense() {
return defense;
}
public void setDefense(int defense) {
this.defense = defense;
}
public int getSpAtk() {
return spAtk;
}
public void setSpAtk(int spAtk) {
this.spAtk = spAtk;
}
public int getSpDef() {
return spDef;
}
public void setSpDef(int spDef) {
this.spDef = spDef;
}
public int getSpeed() {
return speed;
}
public void setSpeed(int speed) {
this.speed = speed;
}
public int getGeneration() {
return generation;
}
public void setGeneration(int generation) {
this.generation = generation;
}
public boolean isLegendary() {
return legendary;
}
public void setLegendary(boolean legendary) {
this.legendary = legendary;
}
public int getCombatScore() {
return (speed/2) * (attack + (spAtk/2)) + (defense + (spDef/2));
}
#Override
public String toString() {
return "Name: " + this.getName()
+ ", Type 1: " + this.getType1()
+ ", Type 2: " + this.getType2()
+ ", Total: " + this.getTotal()
+ ", HP: " + this.getHp()
+ ", Attack: " + this.getAttack()
+ ", Defense: " + this.getDefense()
+ ", Sp. Attack: " + this.getSpAtk()
+ ", Sp. Defense: " + this.getSpDef()
+ ", Generation: " + this.getGeneration()
+ ", Legnedary: " + this.isLegendary()
+ ", Score: " + this.getCombatScore();
}
}
I only want to compare their combatScore values to each other. Any help/suggestions would be much appreciated.
What come to my mind is this. You pick one random item (pokemon) from array list. Remove it from array list. Then you pick one random item again and remove it. Now you have a pair of items. Repeat above step for remaining items in array list until no more items available.
Or you can shuffle whole array list first and then pick item i and item i+1 as pair for i=0,2,4,6,...
Collections.shuffle(pokemonsArrayList);
for (int i=0; i< pokemonsArrayList.size(); i+=2) {
pokemon1 = pokemonsArrayList.get(i);
pokemon2 = pokemonsArrayList.get(i+1);
}
Just make sure that number of elements in ArrayList is even. Otherwise code above will throw exception index out of bound
Since every element in an ArrayList has an index, you can just get a random element from it by calling
Pokemon pokemon1;
Pokemon pokemon2;
pokemon1 = arrayList.get(Math.random()*arrayList.size());
do {
pokemon2 = arrayList.get(Math.random()*arrayList.size());
} while(pokemon1.getId() == pokemon2.getId());
then compare the Pokémon you got out of List1 with the one you got from List2.
You can then of course remove the Pokémon from the List if you wish.
Hope that helps you out!

JAVA - Issues Printing ArrayList

I'm currently attempting to make a lottery program through the use of a GUI. I can not figure out why the method getTicketNumbers() is not returning anything. It is simply printing [].
And so too is:
String output = "Name: " + name + "\nNumbers: " + ticketNumbers + "\n\n";
tickNumbers is outputting [] but name successfully prints out the name.
I added a System.out.print to the Ticket class in the constructor to confirm the ArrayList is being passed successfully and it is:
public Ticket(ArrayList<Integer> ticketNumbers, String name) {
this.ticketNumbers = ticketNumbers;
this.name = name;
System.out.print("Are the numbers being passed:" + ticketNumbers + "\n");
}
The method toString is successfully printing the name but again, it is not printing the ArrayList called ticketNumbers.
private void enterLottoButtonActionPerformed(java.awt.event.ActionEvent evt) {
if (nameInput.getText().equalsIgnoreCase("")) {
JOptionPane.showMessageDialog(null, "Please Enter Your Name", "Error", JOptionPane.ERROR_MESSAGE);
} else if (ticketNumbers.size() < 4) {
JOptionPane.showMessageDialog(null, "Please Enter Four Numbers", "Error", JOptionPane.ERROR_MESSAGE);
} else {
ticketList.add(new Ticket(ticketNumbers, nameInput.getText()));
JOptionPane.showMessageDialog(null, "You Successfully Entered! \n\nName: " + nameInput.getText() + "\nNumbers: " + ticketNumbers.toString());
ticketNumbers.clear();
numbersTextField.setText("");
nameInput.setText("");
numberOfPeopleLabel.setText(" People Entered: " + ticketList.size());
}
Ticket Class:
import java.util.ArrayList;
import java.util.Collections;
import javax.swing.JOptionPane;
public class Ticket {
private String name;
private ArrayList<Integer> ticketNumbers = new ArrayList<>();
public Ticket(ArrayList<Integer> ticketNumbers, String name) {
this.ticketNumbers = ticketNumbers;
this.name = name;
System.out.print("Are the numbers being passed:" + ticketNumbers + "\n");
}
public String getName() {
return name;
}
public ArrayList<Integer> getTicketNumbers() {
return ticketNumbers;
}
public ArrayList<Integer> getSortedTicketNumbers() {
Collections.sort(ticketNumbers);
return ticketNumbers;
}
#Override
public String toString() {
String output = "Name: " + name + "\nNumbers: " + ticketNumbers + "\n\n";
return output;
}
}
If needed, code in its entirety:
http://pastebin.com/7i8VWQLk and http://pastebin.com/iRd49Nc7
ticketNumbers.clear()
This line cause the problem. As you said, during the construction of Ticket object, the data been passed in correctly in this line: ticketList.add(new Ticket(ticketNumbers, nameInput.getText()));. But you cleared them afterwards. You will need a clone of ticketList. Regardless of the best practice, you can do it inside Ticket class.
private List<Integer> clonedTicketNumbersList = new ArrayList<Integer>();
public Ticket(ArrayList<Integer> ticketNumbers, String name) {
this.ticketNumbers = ticketNumbers;
this.name = name;
for(Integer ticketNum : ticketNumbers) {
clonedTicketNumbersList.add(ticketNum );
}
System.out.print("Are the numbers being passed:" + ticketNumbers + "\n");
}
#Override
public String toString() {
String output = "Name: " + name + "\nNumbers: " + clonedTicketNumbersList + "\n\n";
return output;
}
It looks like you're copying the reference to the list, and so when you clear it in one place (or modify it) it changes/clears everywhere.
Try making a defensive copy. Like:
ArrayList<Integer> tickets = new ArrayList<>(ticketNumbers)

How to leave out a null value in a loop in Java

Here's my Java Code:
public class DVD {
public static void main(String[] args) {
DVD newdvd1 = new DVD();
newdvd1.setPlayit("The song is playing \n");
newdvd1.setArtist("Eva Cassidy");
newdvd1.setTitle("Songbird");
newdvd1.setGenre("Blues");
System.out.println(newdvd1.getPlayit());
System.out.println(newdvd1);
DVD newdvd2 = new DVD();
newdvd2.setPlayit("The next song is playing \n");
newdvd2.setArtist("an unknown artist");
newdvd2.setTitle("new song");
System.out.println(newdvd2.getPlayit());
System.out.println(newdvd2);
}
private String artist;
private String title;
private String genre;
private String playit;
public String getPlayit() {
return playit;
}
public void setPlayit(String playit) {
this.playit = playit;
}
public String getArtist() {
return artist;
}
public void setArtist(String artist) {
this.artist = artist;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getGenre() {
return genre;
}
public void setGenre(String genre) {
this.genre = genre;
}
public String toString () {
return ("The artist is called " + artist +
" who is a "+ genre + " singer" +
" and this song is called " + title + ".\n");
}
}
what it outputs is:
The song is playing
The artist is called Eva Cassidy who is a Blues singer and this song is called Songbird.
The next song is playing
The artist is called an unknown artist who is a null singer and this song is called new song.
What i'm asking is, in the second song, how do i leave out 'null singer' as I don't want to display the second songs genre?
Use the ?: (ternary) operator. See JLS specs, for example.
return ("The artist" +
(artist == null ? "" : " is called " + artist) +
(genre == null ? "" : " who is a "+ genre + " singer") +
(title == null ? "" : " and this song is called " + title) +
".\n");
If the given property is not null, you print the relevant text, otherwise simply print nothing.
You can also define sensible default values like:
(artist == null ? " is unknown" : "is called " + artist) +
You can try this.
public String toString() {
StringBuilder builder = new StringBuilder();
if (artist != null && !artist.isEmpty()) {
builder.append("The artist is called : " + artist);
}
if (genre != null && !genre.isEmpty()) {
builder.append(" who is a " + genre + " singer");
}
if (title != null && !title.isEmpty()) {
builder.append(" and this song is called " + title + ".\n");
}
return (builder.toString());
}
If you want the solution to be generic for then modify your toString method as:
public String toString () {
String returnString = "The artist is called " + artist ;
if(genre !=null && !"".equals(genre.trim())) {
returnString += " who is a "+ genre + " singer" +;
}
returnString += " and this song is called " + title + ".\n";
return returnString;
}
You can add more null checks if required for artist and title as well.
You should override toString() using some condition
public String toString () {
if(genre!=null){
return ("The artist is called " + artist +
" who is a "+ genre + " singer" +
" and this song is called " + title + ".\n");
}else{
return ("The artist is called " + artist +
" and this song is called " + title + ".\n");
}
}
If its just about the singer, you could do the following:
public String toString() {
String temp = "The artist is called " + artist";
if(singer != null){ //checks if the object "singer" is not null
temp+=" who is a " + genre + " singer";
}
temp+="and this song is called "+ title + ".\n";
return temp;
}
You can insert a null check to skip this part. Anyway you should use a StringBuffer for that otherwise you are creating many String objects and make the GC angry. Every + creates a new String Object, so with a StringBuffer you only create one String at the end.
public String toString ()
{
StringBuffer buffer = new StringBuffer("The artist is called ");
buffer.append(artist);
if(genre != null)
{
buffer.append(" who is a ");
buffer.append(genre);
buffer.append(" singer");
}
buffer.append(" and this song is called ");
buffer.append(title);
buffer.append(".\n");
return buffer.toString();
}

How can I print out in columns in java

This is where I am printing out and I need it to print in columns.aLeaderboard is an array list with a custom class.it contains several different ints
System.out.println("Position Team Games Played Home Wins Home Draws Home Losses Home Goals For Home Goals Against Away Wins Away Draws Away Losses Away Goals For Away Goals Against Goal Difference Total Points");
for(int counter = 0;counter<teamName.size();counter++)
{
System.out.print((counter + 1) + " " + teamName.get(counter) + " " + (aLeaderboard.get(counter)).getGamesPlayed() + " " + (aLeaderboard.get(counter)).getHomeWins() + " " + (aLeaderboard.get(counter)).getHomeDraws() + " ");
System.out.print((aLeaderboard.get(counter)).getHomeLosses() + " " + (aLeaderboard.get(counter)).getAwayWins() + " " + (aLeaderboard.get(counter)).getAwayWins() + " " + (aLeaderboard.get(counter)).getAwayDraws() + " ");
System.out.print((aLeaderboard.get(counter)).getHomeGoalsFor() + " " + (aLeaderboard.get(counter)).getHomeGoalsAgainst() + " " + (aLeaderboard.get(counter)).getAwayLosses() + " " + (aLeaderboard.get(counter)).getGamesPlayed() + " ");
System.out.print((aLeaderboard.get(counter)).getAwayGoalsFor() + " " + (aLeaderboard.get(counter)).getAwayGoalsAgainst() + " " + (aLeaderboard.get(counter)).getGoalsDifference() + " " + (aLeaderboard.get(counter)).getTotalPoints());
System.out.println();
}
I would use System.out.printf(...) and use a template String to help be sure that all columns line up. Then you could print things out easily in a for loop.
For example:
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.List;
public class Foo4 {
public static void main(String[] args) {
List<Bar4> bar4List = new ArrayList<>();
bar4List.add(new Bar4("Donald", 3, "A", 22.42));
bar4List.add(new Bar4("Duck", 100, "B", Math.PI));
bar4List.add(new Bar4("Herman", 20, "C", Math.sqrt(20)));
String titleTemplate = "%-10s %6s %6s %9s%n";
String template = "%-10s %6d %6s %9s%n";
System.out.printf(titleTemplate, "Name", "Value", "Grade", "Cost");
for (Bar4 bar4 : bar4List) {
System.out.printf(template, bar4.getName(),
bar4.getValue(), bar4.getGrade(), bar4.getCostString());
}
}
}
class Bar4 {
private String name;
private int value;
private String grade;
private double cost;
private NumberFormat currencyFormat = NumberFormat.getCurrencyInstance();
public Bar4(String name, int value, String grade, double cost) {
this.name = name;
this.value = value;
this.grade = grade;
this.cost = cost;
}
public String getName() {
return name;
}
public int getValue() {
return value;
}
public String getGrade() {
return grade;
}
public double getCost() {
return cost;
}
public String getCostString() {
return currencyFormat.format(cost);
}
}
Which would return:
Name Value Grade Cost
Donald 3 A $22.42
Duck 100 B $3.14
Herman 20 C $4.47
For more details on the user of the String format specifiers (i.e., the %6d and %6s above), please look at the Formatter API.

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