What I want to do is set a String called nameWithYear to be equal to be movies[0] + "(" + movies[1]+")" (So "Movie Title (Year)") from text being parsed off a CSV.
Whenever I try, I am experiencing an issue where I keep on getting an array out of bounds error. I tried setting the string equal to only movies[0], it works with success. When I try to set it to movies[1] by itself, it fails. I can do a System.out that includes element [1], and it outputs just fine with no issues. So in other words, for some reason, I can only include element[0] in the string and not element[1]. So I am assuming it has something to do with declaring the value for the string. Just not sure what.
The code is as follows:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class CSVParsing {
public String parseCSV() {
String csvFile = "C:\\Users\\RAY\\Desktop\\movies.csv";
BufferedReader br = null;
String nameWithYear = new String();
String line = "";
String csvSplitBy = ",";
try {
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
if (line.charAt(0) == '"')
{
csvSplitBy = "\",";
}
else
{
csvSplitBy = ",";
}
String[] movies = line.split(csvSplitBy);
nameWithYear = ""+ movies[0]+" ("+movies[1]+")";
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return nameWithYear;
}
public static void main (String[] args)
{
CSVParsing obj = new CSVParsing();
String testString = obj.parseCSV();
}
}
Note that it is not 100% complete, I am testing it in small chunks to make sure it is doing everything as I want it to do.
UPDATE: Found out that it was related to blank year entries as part of the CSV. How do I handle that? The program cuts off once it finds the year entry to be blank.
UPDATE 2: I solved it with my own but of research. I am taking the results after the split() and putting them into an ArrayList. That way, I could handle blank entries in the year column by replacing them with another value.
I guess problem is with your input file.Make sure your input is not of the form
"cauchy hep(21\10\1991) ","cauchy hep" .Notice the space between ) and " remove the space if any since:
if (line.charAt(0) == '"')
{
csvSplitBy = "\",";
}
else
{
csvSplitBy = ",";
}
csvSplitBy equals "\"," no space with the last character of string. If your file doesn't follow the pattern you specified whole line or whole file wil be treated as single string and will be stored in movies[0] .So there will no string at index 1 of movies that's why ArrayIndexOutOfBound.
Remove the space Or you can include the space the beginning " \"," again notice the space between " \"," .It will solve the problem.
split() method returns one element in the array this means that the separator does not exist in the line variable.
line.contains(csvSplitBy);// will be evaluated to false in case of one item is returned by split();
Make sure that the CSV file is comma separated .. or the data has more than one column (CSV formatted correctly )
I hope this could help!
Related
I created a list in a FlightBookingSystem Java Class, as you can see below:
public List<Flight> getFlights() {
List<Flight> out = new ArrayList<>(flights.values());
return Collections.unmodifiableList(out);
}
Which I imported from a text file show below:
1::LX2500::Birmingham::Munich::2020-11-25::
2::LX2500::Denmark::London::2021-07-01::
3::LY2380::London::France::2021-06-28::
It's a basic text file which holds the information for each flight
Here is the code I wish to adjust:
public Flight execute(FlightBookingSystem flightBookingSystem, int id)
throws FlightBookingSystemException {
List<Flight> flights = flightBookingSystem.getFlights();
for (Flight Flight : flights) {
if (Flight.getFlightNumber() == flightNumber) {
System.out.println(Flight.getFlightNumber() + " flight(s)");
return flights.get(id);
}
System.out.println(((Flight) flights).getFlightNumber() + " flight(s)");
}
return flights.get(id);
}
How do I change that code so that it allows the user to retrieve one single record from the text file?
Why not to retrieve all and get the one you want by key or id using HashMap ?
If you still want the other option, you can read the text file line by line, and check if it startsWith(...) and the to retrieve this line.
Code example:
try (BufferedReader br = new BufferedReader(new FileReader(file)))
{
String line;
while ((line = br.readLine()) != null)
{
// Add here 'if' condition and parse your line
}
}
Your question is a bit confusing. Your title states:
How do you allow a user to retrieve values from a list in Java?
and the very last line of your post states:
How do I change that code so that it allows the user to retrieve
one single record from the text file?
Which is it, from a List or from a text file?
If it's from a List because you already have the mechanism available then is could be something similar to this:
public String getFlightInfo(String flightNumber) {
List<Flight> flights = FlightBookingSystem.getFlights();
for (Flight flite : flights) {
if(flite.getFlightNumber().equalsIgnoreCase(flightNumber)){
return flite.toString();
}
}
JOptionPane.showMessageDialog(null, "<html>Flight number <font color=red><b>"
+ flightNumber + "</b></font> could not be found!</html>", "Flight Not "
+ "Found", JOptionPane.INFORMATION_MESSAGE);
return null;
}
The code above assumes you have an overriden toString() method applied to the Flight class. If you don't then create one.
If it's actually from file then it could be something like this:
public String getFlightInfo(String flightNumber) {
// 'Try With Resouces' to auto-close reader.
try (BufferedReader reader = new BufferedReader(new FileReader("Flights.txt"))) {
String fileLine = "";
while ((fileLine = reader.readLine()) != null) {
fileLine = fileLine.trim();
// If by chance the file line read in is blank then skip it.
if (fileLine.isEmpty()) {
continue;
}
// First, remove the double colons at the end of line (if any).
if (fileLine.endsWith("::")) {
fileLine = fileLine.substring(0, fileLine.lastIndexOf("::")).trim();
}
/* Split each read in file line based on a double colon delimiter.
The "\\s*" within the regex for the split method handles any
cases where the might be one or more whitespaces before or after
the double-colon delimiter. */
String[] lineParts = fileLine.split("\\s*\\:\\:\\s*");
if(lineParts[1].equalsIgnoreCase(flightNumber)){
// At this point you could just return the line, for example:
// return fileLine;
// or you can return a string with a little more structure:
return new StringBuilder("Flight ID: ").append(lineParts[0])
.append(", Flight #: ").append(lineParts[1]).append(", From: ")
.append(lineParts[2]).append(", To: ").append(lineParts[3])
.append(", Date: ").append(lineParts[4]).toString();
}
}
}
catch (FileNotFoundException ex) {
JOptionPane.showMessageDialog(null, ex.getMessage());
}
catch (IOException ex) {
JOptionPane.showMessageDialog(null, ex.getMessage());
}
JOptionPane.showMessageDialog(null, "<html>Flight number <font color=red><b>"
+ flightNumber + "</b></font> could not be found!</html>", "Flight Not "
+ "Found", JOptionPane.INFORMATION_MESSAGE);
return null;
}
I have the following Text:
1
(some text)
/
2
(some text)
/
.
.
/
8519
(some text)
and I want to split this text into several text-files where each file has the name of the number before the text i.e. (1.txt, 2.txt) and so on, and the content of this file will be the text.
I tried this code
BufferedReader br = new BufferedReader(new FileReader("(Path)\\doc.txt"));
try {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
// sb.append(System.lineSeparator());
line = br.readLine();
}
String str = sb.toString();
String[] arrOfStr = str.split("/");
for (int i = 0; i < arrOfStr.length; i++) {
PrintWriter writer = new PrintWriter("(Path)" + arrOfStr[i].charAt(0) + ".txt", "UTF-8");
writer.println(arrOfStr[i].substring(1));
writer.close();
}
System.out.println("Done");
} finally {
br.close();
}
this code works for files 1-9. However, things go wrong for files 10-8519 since I took the first number in the string (arrOfStr [i].charAt(0)) I know my solution is insufficient any suggestions?
In addition to my comment, considering there isn't a space between the leading integer and the first word, the substring at the first space doesn't work.
This question/answer has a few options that should help, the one using regex (\d+) being the simplest one imo, and copied below.
Matcher matcher = Pattern.compile("\\d+").matcher(arrOfStr[i]);
matcher.find();
int yourNumber = Integer.valueOf(matcher.group());
Given a string find the first embedded occurrence of an integer
As you mentioned, the problem is that you only take the first digit. You could enumerate the first characters until you find a non digit character ( arrOfStr[i].charAt(j) <'0' || arrOfStr[i].charAt(j) > '9' ) but it shoud be easier to user a Scanner and an appropriate regexp.
int index = new Scanner(arrOfStr[i]).useDelimiter("\\D+").nextInt();
The delimiter is precisely any group of non-digit character
Here is a quick solution for the given problem. You can test and do proper exception handling.
package practice;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.List;
public class FileNioTest {
public static void main(String[] args) {
Path path = Paths.get("C:/Temp/readme.txt");
try {
List<String> contents = Files.readAllLines(path);
StringBuffer sb = new StringBuffer();
String folderName = "C:/Temp/";
String fileName = null;
String previousFileName = null;
// Read from the stream
for (String content : contents) {// for each line of content in contents
if (content.matches("-?\\d+")) { // check if it is a number (based on your requirement)
fileName = folderName + content + ".txt"; // create a file name with path
if (sb != null && sb.length() > 0) { // this means if content present to write in the file
writeToFile(previousFileName, sb); // write to file
sb.setLength(0); // clearing buffer
}
createFile(fileName); // create a new file if number found in the line
previousFileName = fileName; // store the name to write content in previous opened file.
} else {
sb.append(content); // keep storing the content to write in the file.
}
System.out.println(content);// print the line
}
if (sb != null && sb.length() > 0) {
writeToFile(fileName, sb);
sb.setLength(0);
}
} catch (IOException ex) {
ex.printStackTrace();// handle exception here
}
}
private static void createFile (String fileName) {
Path newFilePath = Paths.get(fileName);
if (!Files.exists(newFilePath)) {
try {
Files.createFile(newFilePath);
} catch (IOException e) {
System.err.println(e);
}
}
}
private static void writeToFile (String fileName, StringBuffer sb) {
try {
Files.write(Paths.get(fileName), sb.toString().getBytes(), StandardOpenOption.APPEND);
}catch (IOException e) {
System.err.println(e);
}
}
}
I am trying to iterate through a CSV file in Java. It iterates through the entire file, but will get to the end of the file and try to read the next blank line and throw an error. My code is below.
public class Loop() {
public static void main(String[] args) {
BufferedReader br = null;
String line = "";
try {
HashMap<Integer, Integer> changeData = new HashMap<Integer, Integer>();
br = new BufferedReader(new FileReader("C:\\xxxxx\\xxxxx\\xxxxx\\the_file.csv"));
String headerLine = br.readLine();
while ((line = br.readLine()) != null) {
String[] data = line.split(",");
/*Below is my latest attempt at fixing this,*/
/*but I've tried other things too.*/
if (data[0].equals("")) { break; }
System.out.println(data[0] + " - " + data[6]);
int changeId = Integer.parseInt(data[0]);
int changeCv = Integer.parseInt(data[6]);
changeData.put(changeId, changeCv);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Like I typed, this works fine until it gets to the end of the file. When it gets to the end of the file, I get the error Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at com.ucg.layout.ShelfTableUpdates.main(ShelfTableUpdates.java:23). I've stepped through the code by debugging it in Spring Tool Suite. The error comes up whenever I try to reference data[0] or data[6]; likely because there is nothing in that line. Which leads me back to my original question of why it is even trying to read the line in the first place.
It was my understanding that while ((line = br.readLine()) != null) would detect the end of the file, but it doesn't seem to be. I've tried re-opening the file and deleting all of the blank rows, but that did not work.
Any idea how I can detect the end of the file so I don't get an error in this code?
ANSWER:
Credit goes to user #quemeraisc. I also was able to replace the commas with blanks, and if the line then equals null or "", then you know that it is the end of the file; in my case, there are no blank rows before the end of the file. This still does not solve the problem of detecting the end of the file in that if I did have blank rows in between my data that were not the EOF then this would detect those.
Solution 1:
if (data.length < 7) {
System.out.println(data.length);
break;
}
Solution 1:
if (line.replace(",", "").equals(null) || line.replace(",", "").equals("")) {
System.out.println(line.replace(",", ""));
break;
}
Just skip all blank lines:
while ((line = br.readLine()) != null) {
if( line.trim().isEmpty() ) {
continue;
}
....
....
The last line may contain some control characters (like new line, carriage return, EOF and others unvisible chars), in this case a simple String#trim() doesn't remove them, see this answer to know how to remove them: How can i remove all control characters from a java string?
public String readLine() will read a line from your file, even empty lines. Thus, when you split your line, as in String[] data = line.split(","); you get an array of size 1.
Why not try :
if (data.length >= 7)
{
System.out.println(data[0] + " - " + data[6]);
int changeId = Integer.parseInt(data[0]);
int changeCv = Integer.parseInt(data[6]);
changeData.put(changeId, changeCv);
}
which will make sure there are at least 7 elements in your array before proceeding.
To skip blank lines you could try:
while ((line = reader.readLine()) != null) {
if(line.length() > 0) {
String[] data = line.split(",");
/*Below is my latest attempt at fixing this,*/
/*but I've tried other things too.*/
if (data[0] == null || data[0].equals("")) { break; }
System.out.println(data[0] + " - " + data[6]);
int changeId = Integer.parseInt(data[0]);
int changeCv = Integer.parseInt(data[6]);
changeData.put(changeId, changeCv);
}
}
Instead of replace method use replaceAll method. Then it will work.
I have a text file named "message.txt" which is read using Buffer Reader. Each line of the text file contains both "word" and "meaning" as given in this example:
"PS:Primary school"
where PS - word, Primary school - meaning
When the file is being read, each line is tokenized to "word" and "meaning" from ":".
If the "meaning" is equal to the given input string called "f_msg3", "f_msg3" is displayed on the text view called "txtView". Otherwise, it displays "f_msg" on the text view.
But the "if condition" is not working properly in this code. For example if "f_msg3" is equal to "Primary school", the output on the text view must be "Primary school". But it gives the output as "f_msg" but not "f_msg3". ("f_msg3" does not contain any unnecessary strings.)
Can someone explain where I have gone wrong?
try {
BufferedReader file = new BufferedReader(new InputStreamReader(getAssets().open("message.txt")));
String line = "";
while ((line = file.readLine()) != null) {
try {
/*separate the line into two strings at the ":" */
StringTokenizer tokens = new StringTokenizer(line, ":");
String word = tokens.nextToken();
String meaning = tokens.nextToken();
/*compare the given input with the meaning of the read line */
if(meaning.equalsIgnoreCase(f_msg3)) {
txtView.setText(f_msg3);
} else {
txtView.setText(f_msg);
}
} catch (Exception e) {
txtView.setText("Cannot break");
}
}
} catch (IOException e) {
txtView.setText("File not found");
}
Try this
............
meaning = meaning.replaceAll("\\s+", " ");
/*compare the given input with the meaning of the read line */
if(meaning.equalsIgnoreCase(f_msg3)) {
txtView.setText(f_msg3);
} else {
txtView.setText(f_msg);
}
............
Otherwise comment the else part, then it will work.
I don't see any obvious error in your code, maybe it is just a matter
of cleaning the string (i.e. removing heading and trailing spaces, newlines and so on) before comparing it.
Try trimming meaning, e.g. like this :
...
String meaning = tokens.nextToken();
if(meaning != null) {
meaning = meaning.trim();
}
if(f_msg3.equalsIgnoreCase(meaning)) {
txtView.setText(f_msg3);
} else {
txtView.setText(f_msg);
}
...
A StringTokenizer takes care of numbers (the cause for your error) and other "tokens" - so might be considered to invoke too much complexity.
String[] pair = line.split("\\s*\\:\\s*", 2);
if (pair.length == 2) {
String word = pair[0];
String meaning = pair[1];
...
}
This splits the line into at most 2 parts (second optional parameter) using a regular expression. \s* stands for any whitespace: tabs and spaces.
You could also load all in a Properties. In a properties file the format key=value is convention, but also key:value is allowed. However then some escaping might be needed.
ArrayList vals = new ArrayList();
String jmeno = "Adam";
vals.add("Honza");
vals.add("Petr");
vals.add("Jan");
if(!(vals.contains(jmeno))){
vals.add(jmeno);
}else{
System.out.println("Adam je už v seznamu");
}
for (String jmena : vals){
System.out.println(jmena);
}
try (BufferedReader br = new BufferedReader(new FileReader("dokument.txt")))
{
String aktualni = br.readLine();
int pocetPruchodu = 0;
while (aktualni != null)
{
String[] znak = aktualni.split(";");
System.out.println(znak[pocetPruchodu] + " " +znak[pocetPruchodu + 1]);
aktualni = br.readLine();
}
br.close();
}
catch (IOException e)
{
System.out.println("Nezdařilo se");
}
try (BufferedWriter bw = new BufferedWriter(new FileWriter("dokument2.txt")))
{
int pocetpr = 0;
while (pocetpr < vals.size())
{
bw.write(vals.get(pocetpr));
bw.append(" ");
pocetpr++;
}
bw.close();
}
catch (IOException e)
{
System.out.println("Nezdařilo se");
}
I want to implementing a Java program that searches a phrase example “red or green, blue car, red and blue” in a text file, and returns a match even if it is not a complete match for the phrase, and if there is no even half match the program should return no match.
if I am searching "red car" and the the string line in the text file contains "red and blue" I want the program to return red which is half a match of what I was searching.
Any help is very much appreciated
This is what I have done so far, all this does is find the exact words
public class StringSearch
{
public static void main(String[] args)
{
String key = "red yellow";
String strLine;
try
{
FileInputStream fstream = new FileInputStream("C:\\textfile.txt");
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
while ((strLine = br.readLine()) != null) {
if(key.equals(strLine))
{
System.out.println(" Match For " + strLine );
}
else
{
System.out.println( "No Match For " + key);
}
// Print the content on the console
}
//Close the input stream
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}
But what I want to find is if I am searching "red" and the first line of the string in the text file I am searching contains "red car was stollen" and the second line contains just "red". I want to return two matches the first one being 100% match the socond being 50% match.
First you need to define your problem better, and to do that think about how what you'd do if you were telling someone else, who interpreted things very literally, how to do it. How much of the input should they examine at one time? Should what they examine span lines? What precisely is a "half match"? What is the sequence of steps they should take?
This code might help You
import java.io.*;
public class searchfile {
public static void main(String args[]) {
try {
// Open the file c:\test.txt as a buffered reader
BufferedReader bf = new BufferedReader(new FileReader("c:\\test.txt"));
// Start a line count and declare a string to hold our current line.
int linecount = 0;
String line;
// Let the user know what we are searching for
System.out.println("Searching for " + args[0] + " in file...");
// Loop through each line, stashing the line into our line variable.
while (( line = bf.readLine()) != null)
{
// Increment the count and find the index of the word
linecount++;
int indexfound = line.indexOf(args[0]);
// If greater than -1, means we found the word
if (indexfound > -1) {
System.out.println("Word was found at position " + indexfound + " on line " + linecount);
}
}
// Close the file after done searching
bf.close();
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
}
}
and run it as
c:\>java searchfile "bluecar"