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What am I missing? NumberFormatException error

I want to read from a txt file which contains just numbers. Such file is in UTF-8, and the numbers are separated only by new lines (no spaces or any other things) just that. Whenever i call Integer.valueOf(myString), i get the exception.
This exception is really strange, because if i create a predefined string, such as "56\n", and use .trim(), it works perfectly. But in my code, not only that is not the case, but the exception texts says that what it couldn't convert was "54856". I have tried to introduce a new line there, and then the error text says it couldn't convert "54856
"
With that out of the question, what am I missing?
File ficheroEntrada = new File("C:\\in.txt");
FileReader entrada =new FileReader(ficheroEntrada);
BufferedReader input = new BufferedReader(entrada);
String s = input.readLine();
System.out.println(s);
Integer in;
in = Integer.valueOf(s.trim());
System.out.println(in);
The exception text reads as follows:
Exception in thread "main" java.lang.NumberFormatException: For input string: "54856"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
at java.base/java.lang.Integer.parseInt(Integer.java:658)
at java.base/java.lang.Integer.valueOf(Integer.java:989)
at Quicksort.main(Quicksort.java:170)
The file in.txt consists of:
54856
896
54
53
2
5634

Well, aparently it had to do with Windows and those \r that it uses... I just tried executing it on a Linux VM and it worked. Thanks to everyone that answered!!

Try reading the file with Scanner class has use it's hasNextInt() method to identify what you are reading is Integer or not. This will help you find out what String/character is causing the issue
public static void main(String[] args) throws Exception {
File ficheroEntrada = new File(
"C:\\in.txt");
Scanner scan = new Scanner(ficheroEntrada);
while (scan.hasNext()) {
if (scan.hasNextInt()) {
System.out.println("found integer" + scan.nextInt());
} else {
System.out.println("not integer" + scan.next());
}
}
}

If you want to ensure parsability of a string, you could use a Pattern and Regex that.
Pattern intPattern = Pattern.compile("\\-?\\d+");
Matcher matcher = intPattern.matcher(input);
if (matcher.find()) {
int value = Integer.parseInt(matcher.group(0));
// ... do something with the result.
} else {
// ... handle unparsable line.
}
This pattern allows any numbers and optionally a minus before (without whitespace). It should definetly parse, unless it is too long. I don't know how it handles that, but your example seems to contain mostly short integers, so this should not matter.

Most probably you have a leading/trailing whitespaces in your input, something like:
String s = " 5436";
System.out.println(s);
Integer in;
in = Integer.valueOf(s.trim());
System.out.println(in);
Use trim() on string to get rid of it.
UPDATE 2:
If your file contains something like:
54856\n
896
54\n
53
2\n
5634
then use following code for it:
....your code
FileReader enter = new FileReader(file);
BufferedReader input = new BufferedReader(enter);
String currentLine;
while ((currentLine = input.readLine()) != null) {
Integer in;
//get rid of non-numbers
in = Integer.valueOf(currentLine.replaceAll("\\D+",""));
System.out.println(in);
...your code

comparison of each line in two file

I have a task to compare lines in two files.. values stores in files as string. I am new to Java so please forgive if there is some silly mistake :)
file1 contains
1044510=>40000
2478436011=>10000
2478442011=>3500
2498736011=>3000
2498737011=>550
2478443011=>330
2478444011=>1,550
File two contains
1044510=>30,097
2478436011=>9,155
2478442011=>2,930
2498736011=>2,472
2498737011=>548
2478443011=>313
2478444011=>1,550
I want to take line one from first file and second file and check if value of line1 from first file is greater than second file or not. (40000>30,097) or not. Dont want to take values before "=>".
I have done a sample code but i am getting error while running.
private static void readfiles() throws IOException {
BufferedReader bfFirst = new BufferedReader(new FileReader(first_list));
BufferedReader bfSecond = new BufferedReader(new FileReader(second_list));
int index = 0;
while (true) {
String partOne = bfFirst.readLine();
String partTwo = bfSecond.readLine();
String firstValue=null;
String secondValue=null;
int firstValueInt;
int secondValueInt;
if (partOne == null || partTwo == null)
{
break;
}
else
{
System.out.println(partOne + "-----\t-----" + partTwo);
firstValue=partOne.split("=>")[1];
secondValue=partTwo.split("=>")[1];
System.out.println("first valueee"+firstValue);
System.out.println("second value"+secondValue);
firstValueInt=Integer.parseInt(firstValue);
secondValueInt=Integer.parseInt(secondValue);
if(secondValueInt>firstValueInt)
{
System.out.println("greater");
}
else
{
System.out.println("lesser");
}
}
}
}
}
This is the exception i get
Exception in thread "main" java.lang.NumberFormatException: For input string: "30,097"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:492)
at java.lang.Integer.parseInt(Integer.java:527)
at com.bq.pricefinder.flipkart.findProductDifferenceFromFiles.readfiles(findProductDifferenceFromFiles.java:45)
at com.bq.pricefinder.flipkart.findProductDifferenceFromFiles.main(findProductDifferenceFromFiles.java:18)

The problem here is that you are parsing decimal value as integer.
The exception
java.lang.NumberFormatException: For input string: "30,097"
is clear which says that decimal value 30,097 in an invalid format for an integer.
Use float instead of int, and then compare. Also, sometimes it depends on the locale what decimal symbol is used, it can be , for one country and . for another. Read also THIS.

Integer.parseInt can't work on strings containing non-digits. That's the cause of the NumberFormatException. Use it like this :
firstValueInt=Integer.parseInt(firstValue.replaceAll(",",""));
secondValueInt=Integer.parseInt(secondValue.replaceAll(",",""));

you can get integer only by adding this lines
firstValue = firstValue.replaceAll("[^0-9]", "");
secondValue = secondValue.replaceAll("[^0-9]", "");
then convert it to integer

How to split string by new lines in JAVA?

I want to split string by new lines in Java.I am using following regex -
str.split("\\r|\\n|\\r\\n");
But still it is not splitting string by new lines.
Input -
0
0
0
0
Output = String [] array = {"0000"} instead I want = String [] array = {"0","0","0","0"}.
I have read various solutions on stack overflow but nothing works for me.
Code is -
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DecimalFormat;
public class Input {
public static void main(String[] args) {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String line;
String text = "";
try {
while((line=br.readLine())!=null){
text = text + line;
}
} catch (IOException e) {
e.printStackTrace();
}
String [] textarray = text.trim().split("[\\r\\n]+");
for(int j=0;j<textarray.length;j++)
System.out.println(textarray[j]);
// System.out.print("");
// for(int i=((textarray.length)-1);i>=0;i--){
// long k = Long.valueOf(textarray[i]).longValue();
// System.out.println(k);
//// double sqrt = Math.sqrt(k);
//// double value = Double.parseDouble(new DecimalFormat("##.####").format(sqrt));
//// System.out.println(value);
////
//// }
}

When you call br.readLine(), the newline characters are stripped from the end of the string. So if you type 0 + ENTER four times, you are trying to split the string "0000".
You would be better to read items in from stdin and store them in an expandable data structure, such as a List<String>. No need to split things if you've already read them separately.

Updated Answer:
If you are reading the inputstreamfrom the keyboard, the \n may not be put into the data correctly. In that case, you may want to choose a new sentinel value.
Original Answer:
I believe you need to create a sentinel value. So if \n is your sentinel value, you could do something like this:
Load the inputstream into a string variable
Go character by character through the string variable checking to see if \n is in the input (you could use a for loop and the substing(i, i+2)
If it is found, then you could add it to an array

BufferedReader gives missing characters

So I am trying to change the format of a text file that has line numbers every couple of lines just to make it cleaner and easier to read. I made a simple program that goes in and replaces all of the first three characters of a line with spaces, these three character spaces are where the numbers can be. The actual text doesn't start until a few more spaces in. When i do this and have the end result printed out it comes out with a diamond with a question mark in it and I'm assuming that this is the result of missing characters. It seems like most of the missing characters are the apostrophe symbol. If anyone could let me know how to fix it i would really appreciate it :)
public class Conversion {
public static void main(String args[]) throws IOException {
BufferedReader scan = null;
try {
scan = new BufferedReader(new FileReader(new File("C:\\Users\\Nasir\\Desktop\\Beowulftesting.txt")));
} catch (FileNotFoundException e) {
System.out.println("failed to read file");
}
String finalVersion = "";
String currLine;
while( (currLine = scan.readLine()) !=null){
if(currLine.length()>3)
currLine = " "+ currLine.substring(3);
finalVersion+=currLine+"\n";
}
scan.close();
System.out.println(finalVersion);
}
}

Instead of using FileReader, use an InputStreamReader with the correct text encoding. I think the strange characters are appearing because you're reading the file with the wrong encoding.
By the way, don't use += with strings in a loop, like you have. Instead, use a StringBuilder:
StringBuilder finalVersion = new StringBuilder();
String currLine;
while ((currLine = scan.readLine()) != null) {
if (currLine.length() > 3) {
finalVersion.append(" ").append(currLine.substring(3));
} else {
finalVersion.append(currLine);
}
finalVersion.append('\n');
}

Trying to parse a string to int from a file. Get NumberFormatException: For input string: "", eaven tho string appears to be an good int string. Java

I have been trying to figure this out for couple of hours now and I hope one of you can help me. I have an file (actually two but thats not important) that have some rows and columns with numbers and blank spaces between. And I'm trying to read those with BufferedReader. And that works great. I can print out the strings & chars however I want. But when I try to parse those strings and chars I get the following error:
Exception in thread "main" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at FileProcess.processed(FileProcess.java:30)
at DecisionTree.main(DecisionTree.java:16)
From what I have found with google I think the error is located in how I read my file.
public class ReadFiles {
private BufferedReader read;
public ReadFiles(BufferedReader startRead) {
read = startRead;
}
public String readFiles() throws IOException {
try {
String readLine = read.readLine().trim();
String readStuff = "";
while(readLine != null) {
readStuff += (readLine + "\n");
readLine = read.readLine();
}
return readStuff;
}
catch(NumberFormatException e) {
return null;
}
}
And for the parsing bit
public class FileProcess {
public String processed() throws IOException {
fileSelect fs = new fileSelect();
ReadFiles tr = new ReadFiles(fs.traning());
String training = tr.readFiles();
ReadFiles ts = new ReadFiles(fs.test());
String test = ts.readFiles();
List liste = new List(14,test.length());
String[] test2 = test.split("\n");
for(int i = 0; i<test2[0].length(); i++) {
char tmp = test.charAt(i);
String S = Character.toString(tmp).trim();
//int i1 = Integer.parseInt(S);
System.out.print(S);
}
This isn't the actual code for what I planning to do with the output, but the error appears at the code that is commented out. So my string output is as following:
12112211
Which seems good to parse to integer. But it does not work. I tried to manually see what's in the char position 0 and 1, for 0 I get 1, but for 1 I get nothing aka "". So how can I remove the ""? I hope you guys can help me out, and let me know if you need more info. But I think I have covered what's needed.
Thanks in advance :)
Yeah, and another thing: If I replace "" with "0" it works, but then I get all those zeros which I can't find a clever way to remove. But is it possible to maybe skip them while parsing or something? My files only hold 1 and 2, so it wouldn't interfere with anything if it is possible.

The string "" will be returned if you have 2 of the splitting characters next to each other (i.e. \n\n) or if there is a whitespace character being passed into the trim() call so ignore empty strings and carry on.

You could use the Scanner class to parse for ints, skipping Whitespace:
sc = new java.util.Scanner (line);
sc.nextInt ();
Another idea is to trim the line, split, and parse the parts:
lin = line.trim ();
String [] words = lin.split (" +");
for (String si : words)
Integer.parseInt (si);