I am trying to write a program that uses two classes to find the total $ amount from a text file of retail transactions. The first class must read the file, and the second class must perform the calculations. The problem I am having is that in the first class, the ArrayList only seems to get the price of the last item in the file. Here is the input (which is in a text file):
$69.99 3 Shoes
$79.99 1 Pants
$17.99 1 Belt
And here is my first class:
class ReadInputFile {
static ArrayList<Double> priceArray = new ArrayList<>();
static ArrayList<Double> quantityArray = new ArrayList<>();
static String priceSubstring = new String();
static String quantitySubstring = new String();
public void gatherData () {
String s = "C:\\filepath";
try {
FileReader inputFile = new FileReader(s);
BufferedReader bufferReader = new BufferedReader(inputFile);
String line;
String substring = " ";
while ((line = bufferReader.readLine()) != null)
substring = line.substring(1, line.lastIndexOf(" ") + 1);
priceSubstring = substring.substring(0,substring.indexOf(" "));
quantitySubstring = substring.substring(substring.indexOf(" ") + 1 , substring.lastIndexOf(" ") );
double price = Double.parseDouble(priceSubstring);
double quantity = Double.parseDouble(quantitySubstring);
priceArray.add(price);
quantityArray.add(quantity);
System.out.println(priceArray);
} catch (IOException e) {
e.printStackTrace();
}
}
The output and value of priceArray is [17.99], but the desired output is [69.99,79.99,17.99].
Not sure where the problem is, but thanks in advance for any help!
Basically what you have is:
while ((line = bufferReader.readLine()) != null) {
substring = line.substring(1, line.lastIndexOf(" ") + 1);
}
priceSubstring = substring.substring(0,substring.indexOf(" "));
quantitySubstring = substring.substring(substring.indexOf(" ") + 1 , substring.lastIndexOf(" ") );
double price = Double.parseDouble(priceSubstring);
double quantity = Double.parseDouble(quantitySubstring);
priceArray.add(price);
quantityArray.add(quantity);
System.out.println(priceArray);
So all you are doing is creating a substring of the line you just read, then reading the next line, so basically, only the substring of the last will get processed by the remaining code.
Wrap the code in {...} which you want to be executed on each iteration of the loop
For example...
while ((line = bufferReader.readLine()) != null) {
substring = line.substring(1, line.lastIndexOf(" ") + 1);
priceSubstring = substring.substring(0,substring.indexOf(" "));
quantitySubstring = substring.substring(substring.indexOf(" ") + 1 , substring.lastIndexOf(" ") );
double price = Double.parseDouble(priceSubstring);
double quantity = Double.parseDouble(quantitySubstring);
priceArray.add(price);
quantityArray.add(quantity);
System.out.println(priceArray);
}
This will execute all the code within the {...} block for each line of the file
Related
Hi. I'm having the issue in an error of exception. I don't know what is wrong. But please help me fix this. I'm trying to store data from the file to ArrayList and display the data in the ArrayList. Here, I attached my code and data Code and data source.
the NoSuchElementException appears because you are calling input.nextToken(); while input doesn't have any token.It's due to the last empty line of your file listbook.txt. By deleting this line, the exception shouldn't appear.
A proper manner could be to ensure that you have sufficient tokens to retrieve all your fields for a given line.
public class TextFile
{
public static void main(String[] args)
{
try
{
FileReader read = new FileReader("C:\\Users\\ogawi\\Downloads\\listbook.txt");
BufferedReader bf = new BufferedReader(read);
Book B = new Book();
ArrayList<Book> bookList = new ArrayList<Book>();
String data = null;
StringTokenizer input = null;
while((data = bf.readLine()) != null)
{
input = new StringTokenizer(data,";");
//we ensure that we have enough tokens to retrieve all fields
if(input.countTokens() == 6)
{
String title = input.nextToken();
String author = input.nextToken();
String publisher = input.nextToken();
String genre = input.nextToken();
int year = Integer.parseInt(input.nextToken());
int page = Integer.parseInt(input.nextToken());
B = new Book(title, author, publisher, genre, year, page);
bookList.add(B);
}
}
//This part of code has been moved outside the while loop
//to avoid to print the total content of the array each time
//an element is added
int count=0;
for(int i=0;i<bookList.size();i++)
{
B = (Book)bookList.get(i);
System.out.println(B.toString());
System.out.println("=============================");
count++;
}
System.out.println("Number of Books: " + count);
bf.close();
}
catch(FileNotFoundException fnf)
{ System.out.println(fnf.getMessage());}
catch(EOFException eof)
{ System.out.println(eof.getMessage());}
catch(IOException io)
{ System.out.println(io.getMessage());}
finally
{ System.out.println("System end here..TQ!!");}
}
}
This issue is due to the extra line without book information:
You can see the line 31 and 32 in above figure.
To solve this issue you can add one if condition data.contains(";") . Text file has ; delimiter if we check the condition if given line has ; delimiter then it won't cause an issue.
while ((data = bf.readLine()) != null) {
if (data.contains(";")) {
input = new StringTokenizer(data, ";");
String title = input.nextToken();
String author = input.nextToken();
String publisher = input.nextToken();
String genre = input.nextToken();
int year = Integer.parseInt(input.nextToken());
int page = Integer.parseInt(input.nextToken());
B = new Book(title, author, publisher, genre, year, page);
bookList.add(B);
int count = 0;
for (int i = 0; i < bookList.size(); i++) {
B = (Book) bookList.get(i);
System.out.println(B.toString());
System.out.println("=============================");
count++;
}
System.out.println("Number of Books: " + count);
}
}
Here is the screenshot for successful execution of the code.
I have a method that returns a String and I would like to test if it works correctly. For that I have a test.txt-file that I read and compare to the return value of my method. If I print both Strings out they are exactly the same! Somehow assertEquals still fails.. What am I doing wrong here?
Method to test:
public String statement() {
String result = "Rental Record for " + getName() + "\n";
int frequentRenterPoints = 0;
for (Rental each : this.rentals) {
frequentRenterPoints += each.getFrequentRenterPoints();
// show figures for this rental
result += "\t" + each.getMovie().getTitle() + "\t"
+ " (" + each.getMovie().getQuality() + ")"
+ ": "
+ String.valueOf(each.getCharge()) + "\n";
}
// add footer lines
result += "Amount owed is " + String.valueOf(getTotalCharge()) + "\n";
result += "You earned " + String.valueOf(frequentRenterPoints)
+ " frequent renter points";
return result;
}
Test:
#Test
public void statementReturnsCorrectlyFormattedString() throws IOException {
// given
customer = new Customer("ElonMusk");
Movie movieOne = new Movie("IronMan1", PriceCodes.REGULAR, Quality.HD);
Movie movieTwo = new Movie("AvengersEndGame", PriceCodes.NEW_RELEASE, Quality.FOUR_K);
Rental rentalOne = new Rental();
rentalOne.setMovie(movieOne);
rentalOne.setDaysRented(5);
Rental rentalTwo = new Rental();
rentalTwo.setMovie(movieTwo);
rentalTwo.setDaysRented(1);
List<Rental> rentalList = new LinkedList<Rental>();
rentalList.add(rentalOne);
rentalList.add(rentalTwo);
customer.setRentals(rentalList);
String expectedString = "";
try {
expectedString = readFile("test.txt");
System.out.println("expected: " + "\n" +expectedString);
} catch (IOException e) {
throw new IOException("Error reading statementTestFile!", e);
}
// when
String statement = customer.statement();
// then
System.out.println("statement: " + "\n" + statement);
System.out.println(expectedString.equals(statement));
assertEquals(expectedString, statement);
}
Output: expectedString
expected:
Rental Record for ElonMusk
IronMan1 (HD): 6.5
AvengersEndGame (FOUR_K): 5.0
Amount owed is 11.5
You earned 2 frequent renter points
Output: statement
statement:
Rental Record for ElonMusk
IronMan1 (HD): 6.5
AvengersEndGame (FOUR_K): 5.0
Amount owed is 11.5
You earned 2 frequent renter points
readFile:
private String readFile(String file) throws IOException {
BufferedReader reader = new BufferedReader(new FileReader (file));
String line = null;
StringBuilder stringBuilder = new StringBuilder();
String ls = "\n";
try {
while((line = reader.readLine()) != null) {
stringBuilder.append(line);
stringBuilder.append(ls);
}
return stringBuilder.toString();
} finally {
reader.close();
}
}
The problem is in the trailing newline you add when reading from a file. You could in trim the string, but what if there were some empty lines at the end of file you wanted to read?
So you can either introduce a 'first line' boolean like that:
boolean isFirstLine = true;
while((line = reader.readLine()) != null) {
if (!isFirstLine) {
stringBuilder.append(ls);
}
stringBuilder.append(line);
isFirstLine = false;
}
Or maybe leave the loop as-is and after it runs delete last character from the builder with:
if (stringBuilder.length() > 0) {
stringBuilder.deleteCharAt(stringBuilder.length() - 1); // or stringBuilder.lastIndexOf("\n");
}
Or do a substring.
Or maybe read the lines into a List collection like ArrayList and later do String.join("\n", linesCollection);.
How can I count the number of cities per country from the data file? I would also like to display the value as percentage of the total.
import java.util.StringTokenizer;
import java.io.*;
public class city
{
public static void main(String[] args)
{
String[] city = new String[120];
String country = null;
String[] latDegree =new String[120];
String lonDegree =null;
String latMinute =null;
String lonMinute =null;
String latDir = null;
String lonDir = null;
String time = null;
String amORpm = null;
try
{
File myFile = new File("CityLongandLat.txt");
FileReader fr = new FileReader(myFile);
BufferedReader br = new BufferedReader(fr);
String line = null;
int position =0;
int latitude=0;
while( (line = br.readLine()) != null)
{
// System.out.println(line);
StringTokenizer st = new StringTokenizer(line,",");
while(st.hasMoreTokens())
{
city[position] = st.nextToken();
country = st.nextToken();
latDegree[latitude] =st.nextToken();
latMinute =st.nextToken();
latDir = st.nextToken();
lonDegree =st.nextToken();
lonMinute =st.nextToken();
lonDir = st.nextToken();
time = st.nextToken();
amORpm = st.nextToken();
}
if(city.length<8)
{
System.out.print(city[position] + "\t\t");
}
else
{
System.out.print(city[position] + "\t");
}
if(country.length()<16)
{
System.out.print(country +"\t\t");
}
else
{
System.out.print(country);
}
System.out.print(latDegree + "\t");
System.out.print(latMinute + "\t");
System.out.print(latDir + "\t");
System.out.print(lonDegree + "\t");
System.out.print(lonMinute + "\t");
System.out.print(lonDir + "\t");
System.out.print(time + "\t");
System.out.println(amORpm + "\t");
position++;
}
br.close();
}
catch(Exception ex)
{
System.out.println("Error !!!");
}
}
}
One easy way that comes to my mind would be as follows...
Create a hashMap Object where the key is a string (the country) and the value is an integer (number of cities found for the country) so it would be something like
Map countryResultsFoundMap = new HashMap< String,Integer>();
In short, for each row you would pick the country, (I would recommend that you .trim() and .toLowerCase() the value first) and check if it is existing in the hashMap, if not, add the entry like countryResultsFoundMap.put(country,0), otherwise, if the country already exists the pick the value from the hashMAp and add +1 to its integer value.
Eventually you will have all the values stored in the map and you can have access to that data for your calculations.
Hope that helps
"here are some of the output from the data file from my programme"
Aberdeen Scotland 57 2 [Ljava.lang.String;#33906773 9 N [Ljava.lang.String;#4d77c977 9 W 05:00 p.m. Adelaide Australia 34 138 [Ljava.lang.String;#33906773 55 S [Ljava.lang.String;#4d77c977 36 E 02:30 a.m...
The reason why your getting that output, is because you're trying to print the array object latDegree.
String[] latDegree
...
System.out.print(latDegree + "\t");
Also, you have lattitude = 0; but you never increment it, so it will always use the index 0 for the array. You need to increment it, like you did position++.
So for the print statement, print the print the value at index lattitude, not the entire array
Try this
System.out.print(latDegree[lattitude] + "\t");
...
lattitude++;
If for some reason you do want to print the array, then use Arrays.toString(array); or just iterate through it
I would also start with a map, and group the cities by country with a map.
Map<String,<List<String>>
Where the key is the country and the value is the list of cities in this country. With the size() methods you can perform the operations cities per country and percentage of total.
When you read one line you check if the key (country) already exists, if not you create a new list and add the city, otherwise add the city only to the existing list.
As a starter you could use the following snippet. However this sample assumes that the content of the file is read already and given as an argument to the method.
Map<String,List<String>> groupByCountry(List<String> lines){
Map<String,List<String>> group = new HashMap<>();
for (String line : lines) {
String[] tokens = line.split(",");
String city = tokens[0];
String country = tokens[1];
...
if(group.containsKey(country)){
group.get(country).add(city);
}else{
List<String> cities = new ArrayList<>();
cities.add(city);
group.put(country, cities);
}
}
return group;
}
i have a text file that has date/time, name, amount tipped, total tips
I am able to get it reduced to just names (In one arraylist) and amount tipped(in a second arraylist)
Now I'm trying to get it to where it adds up the amount tipped per person.
So if X tipped 10,20,30,40 it will output X tipped 100.
From Text file
Dec. 6, 2013, 8:31 p.m. Tip from y
25 7687
Dec. 6, 2013, 8:30 p.m. Tip from x
30 7662
Dec. 6, 2013, 8:30 p.m. Tip from z
25 7632
Dec. 6, 2013, 8:31 p.m. Tip from z
25 7687
Dec. 6, 2013, 8:30 p.m. Tip from z
30 7662
Dec. 6, 2013, 8:30 p.m. Tip from x
25 7632
Here is where I am at so far
import java.io.*;
import java.util.*;
public class TipTester {
public static void main(String[] args) {
int lineNumber = 1;
List<String> name = new ArrayList<String>();
List<String> tip = new ArrayList<String>();
String fileName = "C:\\Users\\David\\Desktop\\tips.txt";
System.out.println("Reading text from file");
try {
FileReader inputFile = new FileReader(fileName);
BufferedReader bufferedReader = new BufferedReader(inputFile);
String line;
while ((line = bufferedReader.readLine()) != null) {
if (lineNumber % 2 != 0) {
System.out.println(line.substring(line.indexOf("from ") + 5) + "\\");
name.add(line.substring(line.indexOf("from ") + 5) + "\\");
} else {
System.out.println(line.substring(0, line.indexOf("\t")) + "\\");
tip.add(line.substring(0, line.indexOf("\t")) + "\\");
}
lineNumber ++;
}
bufferedReader.close();
name.add("-");
tip.add("-");
} catch (Exception e) {
System.out.println("Error while reading file line by line: " + e.getMessage());
}
}
}
Instead of using two different lists. You can just use a map.
Map<String, Double> map = new HashMap<String, Double>();
while ((line = br.readLine()) != null){
double tip = // get tip from line
String name = // get name from line
if (!map.containsKey(name)){ // if map doesn't contain name
map.put(name, tip); // put in the initial name and tip amount
} else {
double value = map.get(name); // else get the current value from the map
map.put(name, value + tip); // put in the new value to the map
}
}
Now your map contains names and total tips
Edit: If you're using two different lists, you want to keep the name and tips in parallel indices.
You could do something like this
ArrayList<String> nameList = new ArrayList<>();
ArrayList<Integer> tipList = new ArrayList<>();
while ((line = br.readLine()) != null){
String name = // get name from line
int tip = // get tip from next line
if (!nameList.contains(name)){ // if list doesnt contain the name
nameList.add(name); // add the name
tipList.add(tip); // add the tpi
} else {
int index = nameList.indexOf(name); // else get the index of the name
int newTip = tipList.get(index) + tip; // get the tip amount + new tip
tipList.set(index, newTip); // set the tip amount
}
}
Without too much modifications of your code (introduced a Map and used Integer for tips):
package com.stackoverflow.so20560521;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.Map;
public class Tip {
public static void main(String[] args)
{
int lineNumber = 1;
Map<String, Integer> tipsByName = new HashMap<String, Integer>();
String fileName = "C:\\Users\\David\\Desktop\\tips.txt";
System.out.println("Reading text from file");
try {
FileReader inputFile = new FileReader(fileName);
BufferedReader bufferedReader = new BufferedReader(inputFile);
String line;
String currentTipper = null;
while ((line = bufferedReader.readLine()) != null) {
if (lineNumber % 2 != 0) {
final String tipperName = line.substring(line.indexOf("from ") + 5);
System.out.println(tipperName);
currentTipper = tipperName;
} else {
final Integer tipValue = Integer.parseInt(line.substring(0, line.indexOf("\\t")));
System.out.println(tipValue);
// here we store the tip in the map. If we have a record we sum, else
// we store as is
tipsByName.put(currentTipper, (tipsByName.get(currentTipper) == null ? 0 : tipsByName.get(currentTipper))
+ tipValue);
}
lineNumber++;
}
bufferedReader.close();
System.out.println(tipsByName); // output the map
} catch (Exception e) {
System.out.println("Error while reading file line by line: " + e.getMessage());
}
}
}
This outputs
Reading text from file
y
25
x
30
z
25
z
25
z
30
x
25
{z=80, y=25, x=55}
In the input file, there are 2 columns: 1) stem, 2) affixes. In my coding, i recognise each of the columns as tokens i.e. tokens[1] and tokens[2]. However, for tokens[2] the contents are: ng ny nge
stem affixes
---- -------
nyak ng ny nge
my problem here, how can I declare the contents under tokens[2]? Below are my the snippet of the coding:
try {
FileInputStream fstream2 = new FileInputStream(file2);
DataInputStream in2 = new DataInputStream(fstream2);
BufferedReader br2 = new BufferedReader(new InputStreamReader(in2));
String str2 = "";
String affixes = " ";
while ((str2 = br2.readLine()) != null) {
System.out.println("Original:" + str2);
tokens = str2.split("\\s");
if (tokens.length < 4) {
continue;
}
String stem = tokens[1];
System.out.println("stem is: " + stem);
// here is my point
affixes = tokens[3].split(" ");
for (int x=0; x < tokens.length; x++)
System.out.println("affix is: " + affixes);
}
in2.close();
} catch (Exception e) {
System.err.println(e);
} //end of try2
You are using tokens as an array (tokens[1]) and assigning the value of a String.split(" ") to it. So it makes things clear that the type of tokens is a String[] array.
Next,
you are trying to set the value for affixes after splitting tokens[3], we know that tokens[3] is of type String so calling the split function on that string will yield another String[] array.
so the following is wrong because you are creating a String whereas you need String[]
String affixes = " ";
so the correct type should go like this:
String[] affixes = null;
then you can go ahead and assign it an array.
affixes = tokens[3].split(" ");
Are you looking for something like this?
public static void main(String[] args) {
String line = "nyak ng ny nge";
MyObject object = new MyObject(line);
System.out.println("Stem: " + object.stem);
System.out.println("Affixes: ");
for (String affix : object.affixes) {
System.out.println(" " + affix);
}
}
static class MyObject {
public final String stem;
public final String[] affixes;
public MyObject(String line) {
String[] stemSplit = line.split(" +", 2);
stem = stemSplit[0];
affixes = stemSplit[1].split(" +");
}
}
Output:
Stem: nyak
Affixes:
ng
ny
nge