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Reading a File without line breaks using Buffered reader

I am reading a file with comma separated values which when split into an array will have 10 values for each line . I expected the file to have line breaks so that
line = bReader.readLine()
will give me each line. But my file doesnt have a line break. Instead after the first set of values there are lots of spaces(465 to be precise) and then the next line begins.
So my above code of readLine() is reading the entire file in one go as there are no lined breaks. Please suggest how best to efficiently tackle this scenario.

One way is to replace String with 465 spaces in your text with new line character "\n" before iterating it for reading.

I second Ninan's answer: replace the 465 spaces with a newline, then run the function you were planning on running earlier.
For aesthetics and readability I would suggest using Regex's Pattern to replace the spaces instead of a long unreadable String.replace(" ").
Your code could like below, but replace 6 with 465:
// arguments are passed using the text field below this editor
public static void main(String[] args)
{
String content = "DOG,CAT MOUSE,CHEESE";
Pattern p = Pattern.compile("[ ]{6}",
Pattern.DOTALL | Pattern.CASE_INSENSITIVE);
String newString = p.matcher(content).replaceAll("\n");
System.out.println(newString);
}

My suggestion is read file f1.txt and write to anther file f2.txt by removing all empty lines and spaces then read f2.txt something like
FileReader fr = new FileReader("f1.txt");
BufferedReader br = new BufferedReader(fr);
FileWriter fw = new FileWriter("f2.txt");
String line;
while((line = br.readLine()) != null)
{
line = line.trim(); // remove leading and trailing whitespace
if (!line.equals("")) // don't write out blank lines
{
fw.write(line, 0, line.length());
}
}
Then try using your code.

You might create your own subclass of a FilterInputStream or a PushbackInputStream and pass that to an InputStreamReader. One overrides int read().
Such a class unfortunately needs a bit of typing. (A nice excercise so to say.)
private static final int NO_CHAR = -2;
private boolean fromCache;
private int cachedSpaces;
private int cachedNonSpaceChar = NO_CHAR;
int read() throws IOException {
if (fromCache) {
if (cachecSpaces > 0) ...
if (cachedNonSpaceChar != NO_CHAR) ...
...
}
int ch = super.read();
if (ch != -1) {
...
}
return ch;
}
The idea is to cache spaces till either a nonspace char, and in read() either take from the cache, return \n instead, call super.read() when not from cache, recursive read when space.

My understanding is that you have a flat CSV file without proper line break, which supposed to have 10 values on each line.
Updated:
1. (Recommended) You can use Scanner class with useDelimiter to parse csv effectively, assuming you are trying to store 10 values from a line:
public static void parseCsvWithScanner() throws IOException {
Scanner scanner = new Scanner(new File("test.csv"));
// set your delimiter for scanner, "," for csv
scanner.useDelimiter(",");
// storing 10 values as a "line"
int LINE_LIMIT = 10;
// implement your own data structure to store each value of CSV
int[] tempLineArray = new int[LINE_LIMIT];
int lineBreakCount = 0;
while(scanner.hasNext()) {
// trim start and end spaces if there is any
String temp = scanner.next().trim();
tempLineArray[lineBreakCount++] = Integer.parseInt(temp);
if (lineBreakCount == LINE_LIMIT) {
// replace your own logic for handling the full array
for(int i=0; i<tempLineArray.length; i++) {
System.out.print(tempLineArray[i]);
} // end replace
// resetting array and counter
tempLineArray = new int[LINE_LIMIT];
lineBreakCount = 0;
}
}
scanner.close();
}
Or use the BufferedReader.
You might not need the ArrayList to store all values if there is memory issue by replacing your own logic.
public static void parseCsv() throws IOException {
BufferedReader br = new BufferedReader(new FileReader(file));
// your delimiter
char TOKEN = ',';
// your requirement of storing 10 values for each "line"
int LINE_LIMIT = 10;
// tmp for storing from BufferedReader.read()
int tmp;
// a counter for line break
int lineBreakCount = 0;
// array for storing 10 values, assuming the values of CSV are integers
int[] tempArray = new int[LINE_LIMIT];
// storing tempArray of each line to ArrayList
ArrayList<int[]> lineList = new ArrayList<>();
StringBuilder sb = new StringBuilder();
while((tmp = br.read()) != -1) {
if ((char)tmp == TOKEN) {
if (lineBreakCount == LINE_LIMIT) {
// your logic to handle the current "line" here.
lineList.add(tempArray);
// new "line"
tempArray = new int[LINE_LIMIT];
lineBreakCount = 0;
}
// storing current value from buffer with trim of spaces
tempArray[lineBreakCount] =
Integer.parseInt(sb.toString().trim());
lineBreakCount++;
// clear the buffer
sb.delete(0, sb.length());
}
else {
// add current char from BufferedReader if not delimiter
sb.append((char)tmp);
}
}
br.close();
}

Java read specific file store in arraylist

Suppose I would like to read input text file into lists.
File contents:
/* ignore comments */
/*TaskID <space> Duration <space> Dependency <comma> <Dependency>...*/
A 1
B 2 A(-1)
C 3 B,A
D 4 D
How do I avoid reading the comments and store each line in a proper order?
Ex:
task = {A,B,C,D}
duration = {1,2,3,4}
dependency = {, A(-1), BA, D}

Pick that specific file from the list. Read it line by line. Check each line if it is a comment. If Yes, Skip the line and continue. else split the line into words and store those words into an array of String. Put each element to its corresponding list. Note: The conditon if (raw.length < 3) is just used to handle the enter character as you have one at the end of line 4.
public class ReadContents {
public static void main(String[] args) {
ArrayList<File> files = new ArrayList();
ArrayList<String> tasks = new ArrayList();
ArrayList<String> hrs = new ArrayList();
ArrayList<String> others = new ArrayList();
String[] raw;
files.add(new File("File path"));
try (BufferedReader br = new BufferedReader(new FileReader(files.get(0)))) {
String line;
while ((line = br.readLine()) != null) {
if (line.startsWith("/*") | line.equals("")) {
continue;
} else {
raw = line.split("\\s+");
if (raw.length < 3) {
tasks.add(raw[0]);
hrs.add(raw[1]);
others.add("");
}else{
tasks.add(raw[0]);
hrs.add(raw[1]);
others.add(raw[2]);
}
}
}
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}

How do I avoid reading the comments and store each line in a proper order?
The simplest way to avoid comments is to use a simple method for denoting a comment. E.g. starting a line with # is often used to denote comments in simple scripting languages. Thus there is no need to parse for open/close comment contexts as inputs can be treated as whole lines.

Read a text file to an array Java

I know there are many questions about reading text files here but I have gone through all of them and I think I'm having some difficulty with syntax or SOMETHING because nothing that I've been trying has been working at all.
What I'm attempting to do is this:
1) read a text file inputed by user
2) copy each individual line into an array, so each line is its own element in the array
I feel like I am very close but for some reason I can't figure out exactly how to get it to work!
Here is the relevant code I have right now:
I keep getting out of bounds exceptions in three locations which I've marked off.
Been working on this for quite a while not sure what to do next! Any ideas?
import java.io.IOException;
import java.util.Scanner;
public class FindWords {
public static void main (String args[]) throws IOException{
FindWords d = new Dictionary();
((Dictionary) d).dictionary(); //********* out of bounds here
}
/**
* Validates and returns the dictionary inputed by the user.
*
* #param
* #return the location of the dictionary
*/
public static String getDict(){
///////////////////ASK FOR DICTIONARY////////////////////
System.out.println("Please input your dictionary file");
//initiate input scanner
Scanner in = new Scanner(System.in);
// input by user
String dictionary = in.nextLine();
System.out.println("Sys.print: " + dictionary);
//make sure there is a dictionary file
if (dictionary.length() == 0){
throw new IllegalArgumentException("You must enter a dictionary");
}
else return dictionary;
}
}
which calls on the class Dictionary:
import java.io.*;
public class Dictionary extends FindWords{
public void dictionary () throws IOException{
String dict = getDict();
String[] a = readFile(dict); //********** out of bounds here
int i = 0;
while(a[i] != null){
System.out.println(a[i]);
i++;
}
}
public static String[] readFile(String input) throws IOException{
//read file
BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(input)));
System.out.println ();
int count = 0;
String[] array = new String[count];
try{
while (br.readLine() != null){
array[count] = br.readLine(); //********out of bounds here
count++;
}
br.close();
}
catch (IOException e){
}
return array;
}
}
Thank you for looking!
Edit: Just fyi: I have my .txt file in the parent project folder.

Have you tried this?:
List<String> lines = Files.readAllLines(Paths.get("/path/to/my/file.txt"));
and then transform your list to an array if you want:
String[] myLines = lines.toArray(new String[lines.size()]);

You start with an array size of zero...
int count = 0;
String[] array = new String[count];

Several issues here :
In Java, you can't expand arrays, i.e you have to know their length in advance when you instantiate them. Hence the ArrayOutOfBoundException. To make this easy, I suggest that you use an ArrayList instead.
In your while loop, you're making 2 calls to br.readLine(), so basically you're skipping one line out of 2.

You are initializing a zero-length array, hence the exception on the first iteration:
int count = 0;
String[] array = new String[count];
Since you probably don't know the expected size, work with a List instead:
List<String> list = new ArrayList<>();
String thisLine = null;
try{
while ((thisLine = br.readLine()) != null) {
list.add(thisLine);
}
}
You can get the total size afterwards by:
list.size();
Or even better, go with morganos solution and use Files.readAllLines().

Java, problems with string array of (string) array (maybe dynamic)

To speed-up a lookup search into a multi-record file I wish to store its elements into a String array of array so that I can just search a string like "AF" into similar strings only ("AA", "AB, ... , "AZ") and not into the whole file.
The original file is like this:
AA
ABC
AF
(...)
AP
BE
BEND
(...)
BZ
(...)
SHORT
VERYLONGRECORD
ZX
which I want to translate into
AA ABC AF (...) AP
BE BEND (...) BZ
(...)
SHORT
VERYLONGRECORD
ZX
I don't know how much records there are and how many "elements" each "row" will have as the source file can change in the time (even if, after being read into memory, the array is only read).
I tried whis solution:
in a class I defined the string array of (string) arrays, without defining its dimensions
public static String[][] tldTabData;
then, in another class, I read the file:
public static void tldLoadTable() {
String rec = null;
int previdx = 0;
int rowidx = 0;
// this will hold each row
ArrayList<String> mVector = new ArrayList<String>();
FileInputStream fStream;
BufferedReader bufRead = null;
try {
fStream = new FileInputStream(eVal.appPath+eVal.tldTabDataFilename);
// Use DataInputStream to read binary NOT text.
bufRead = new BufferedReader(new InputStreamReader(fStream));
} catch (Exception er1) {
/* if we fail the 1.st try maybe we're working into some "package" (e.g. debugging)
* so we'll try a second time with a modified path (e.g. adding "bin\") instead of
* raising an error and exiting.
*/
try {
fStream = new FileInputStream(eVal.appPath +
"bin"+ File.separatorChar + eVal.tldTabDataFilename);
// Use DataInputStream to read binary NOT text.
bufRead = new BufferedReader(new InputStreamReader(fStream));
} catch (FileNotFoundException er2) {
System.err.println("Error: " + er2.getMessage());
er2.printStackTrace();
System.exit(1);
}
}
try {
while((rec = bufRead.readLine()) != null) {
// strip comments and short (empty) rows
if(!rec.startsWith("#") && rec.length() > 1) {
// work with uppercase only (maybe unuseful)
//rec.toUpperCase();
// use the 1st char as a row index
rowidx = rec.charAt(0);
// if row changes (e.g. A->B and is not the 1.st line we read)
if(previdx != rowidx && previdx != 0)
{
// store the (completed) collection into the Array
eVal.tldTabData[previdx] = mVector.toArray(new String[mVector.size()]);
// clear the collection itself
mVector.clear();
// and restart to fill it from scratch
mVector.add(rec);
} else
{
// continue filling the collection
mVector.add(rec);
}
// and sync the indexes
previdx = rowidx;
}
}
streamIn.close();
// globally flag the table as loaded
eVal.tldTabLoaded = true;
} catch (Exception er2) {
System.err.println("Error: " + er2.getMessage());
er2.printStackTrace();
System.exit(1);
}
}
When executing the program, it correctly accumulates the strings into mVector but, when trying to copy them into the eVal.tldTabData I get a NullPointerException.
I bet I have to create/initialize the array at some point but having problems to figure where and how.
First time I'm coding in Java... helloworld apart. :-)

you can use a Map to store your strings per row;
here something that you'll need :
//Assuming that mVector already holds all you input strings
Map<String,List<String>> map = new HashMap<String,List<String>>();
for (String str : mVector){
List<String> storedList;
if (map.containsKey(str.substring(0, 1))){
storedList = map.get(str.substring(0, 1));
}else{
storedList = new ArrayList<String>();
map.put(str.substring(0, 1), storedList);
}
storedList.add(str);
}
Set<String> unOrdered = map.keySet();
List<String> orderedIndexes = new ArrayList<String>(unOrdered);
Collections.sort(orderedIndexes);
for (String key : orderedIndexes){//get strings for every row
List<String> values = map.get(key);
for (String value : values){//writing strings on the same row
System.out.print(value + "\t"); // change this to writing to some file
}
System.out.println(); // add new line at the end of the row
}

Read one line of a csv file in Java

I have a csv file that currently has 20 lines of data.
The data contains employee info and is in the following format:
first name, last name, Employee ID
So one line would like this: Emma, Nolan, 2
I know how to write to the file in java and have all 20 lines print to the console, but what I'm not sure how to do is how to get Java to print one specific line to the console.
I also want to take the last employee id number in the last entry and have java add 1 to it one I add new employees. I thinking this needs to be done with a counter just not sure how.

You can do something like this:
BufferedReader reader = new BufferedReader(new FileReader(<<your file>>));
List<String> lines = new ArrayList<>();
String line = null;
while ((line = reader.readLine()) != null) {
lines.add(line);
}
System.out.println(lines.get(0));
With BufferedReader you are able to read lines directly. This example reads the file line by line and stores the lines in an array list. You can access the lines after that by using lines.get(lineNumber).

You can read text from a file one line at a time and then do whatever you want to with that line, print it, compare it, etc...
// Construct a BufferedReader object from the input file
BufferedReader r = new BufferedReader(new FileReader("employeeData.txt"));
int i = 1;
try {
// "Prime" the while loop
String line = r.readLine();
while (line != null) {
// Print a single line of input file to console
System.out.print("Line "+i+": "+line);
// Prepare for next loop iteration
line = r.readLine();
i++;
}
} finally {
// Free up file descriptor resources
r.close();
}
// Remember the next available employee number in a one-up scheme
int nextEmployeeId = i;

BufferedReader reader =new BufferedReader(new FileReader("yourfile.csv"));
String line = "";
while((line=reader.readLine())!=null){
String [] employee =line.trim().split(",");
// if you want to check either it contains some name
//index 0 is first name, index 1 is last name, index 2 is ID
}

Alternatively, If you want more control over read CSV files then u can think about CsvBeanReader that will give you more access over files contents..

Here is an algorithm which I use for reading csv files. The most effective way is to read all the data in the csv file into a 2D array first. It just makes it a lot more flexible to manipulate the data.
That way you can specify which line of the file to print to the console by specifying it in the index of the array and using a for. I.e: System.out.println(employee_Data[1][y]); for record 1. y is the index variable for fields. You would need to use a For Loop of course, to print every element for each line.
By the way, if you want to use the employee data in a larger program, in which it may for example store the data in a database or write to another file, I'd recommend encapsulating this entire code block into a function named Read_CSV_File(), which will return a 2D String array.
My Code
// The return type of this function is a String.
// The CSVFile_path can be for example "employeeData.csv".
public static String[][] Read_CSV_File(String CSVFile_path){
String employee_Data[][];
int x;
int y;
int noofFields;
try{
String line;
BufferedReader in = new BufferedReader(new FileReader(CSVFile_path));
// reading files in specified directory
// This assigns the data to the 2D array
// The program keeps looping through until the line read in by the console contains no data in it i.e. the end of the file.
while ( (( line = in.readLine()) != null ){
String[] current_Record = line.split(",");
if(x == 0) {
// Counts the number of fields in the csv file.
noofFields = current_Record.length();
}
for (String str : values) {
employee_Data[x][y] = str;
System.out.print(", "+employee_Data[x][y]);
// The field index variable, y is incremented in every loop.
y = y + 1;
}
// The record index variable, x is incremented in every loop.
x = x + 1;
}
// This frees up the BufferedReader file descriptor resources
in.close();
/* If an error occurs, it is caught by the catch statement and an error message
* is generated and displayed to the user.
*/
}catch( IOException ioException ) {
System.out.println("Exception: "+ioException);
}
// This prints to console the specific line of your choice
System.out.println(("Employee 1:);
for(y = 0; y < noofFields ; y++){
// Prints out all fields of record 1
System.out.print(employee_Data[1][y]+", ");
}
return employee_Data;
}

For reading large file,
log.debug("****************Start Reading CSV File*******");
copyFile(inputCSVFile);
StringBuilder stringBuilder = new StringBuilder();
String line= "";
BufferedReader brOldFile = null;
try {
String inputfile = inputCSVFile;
log.info("inputfile:" + inputfile);
brOldFile = new BufferedReader(new FileReader(inputfile));
while ((line = brOldFile.readLine()) != null) {
//line = replaceSpecialChar(line);
/*do your stuff here*/
stringBuilder.append(line);
stringBuilder.append("\n");
}
log.debug("****************End reading CSV File**************");
} catch (Exception e) {
log.error(" exception in readStaffInfoCSVFile ", e);
}finally {
if(null != brOldFile) {
try {
brOldFile.close();
} catch (IOException e) {
}
}
}
return stringBuilder.toString();