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Trying to replace a symbol in a text file of 4000 lines, ends up with only 500 in Java

What i'm trying to do, is to replace a symbol in a file text which contains over 4000 lines but using the below code, after the program ends, it only remain 500 lines. Why is this file truncated? How to solve this?
This is my code:
ArrayList<String> arrayList = new ArrayList<>();
try (FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader)) {
String line;
while ((line = bufferedReader.readLine()) != null) {
line = line.replace("þ", "t");
arrayList.add(line);
try (BufferedWriter bw = new BufferedWriter(new FileWriter(file))) {
for (String string : arrayList) {
bw.write(string + "\n");
}
} catch (Exception e) {System.err.println(e);}
}
} catch (Exception e) {e.printStackTrace();}
Thanks in advance!

new BufferedWriter(new FileWriter(file)) clear file.
You should open it only once. Also you reading and writing to the same file. You should use different files.
Like this
try (FileReader fileReader = new FileReader(inputFile);
BufferedReader bufferedReader = new BufferedReader(fileReader);
BufferedWriter bw = new BufferedWriter(new FileWriter(outputFile))) {
String line;
while ((line = bufferedReader.readLine()) != null) {
line = line.replace("þ", "t");
bw.write(line + "\n");
}
} catch (Exception e) {
e.printStackTrace();
}

You are writing to the same file while you are reading it. This won't work. Once you start writing, the file becomes empty (plus whatever you've written), so subsequent reads will report end-of-file. Your ~500 lines will be buffered input from the first read.
One solution is to do all the reading first, before opening the file again for writing:
Array<String> arrayList = new ArrayList<>();
try (BufferedReader bufferedReader = new BufferedReader(new FileReader(file))) {
while ((String line = bufferedReader.readLine()) != null) {
line = line.replace("þ", "t");
arrayList.add(line);
}
} catch (Exception e) {
e.printStackTrace();
}
try (BufferedWriter bw = new BufferedWriter(new FileWriter(file))) {
for (String string : arrayList) {
bw.write(string + "\n");
}
} catch (Exception e) {
System.err.println(e);
}
Here, first the program slurps the file into a List<String>, fixing the lines as it goes. Then it writes all the lines back out to the file.
There are circumstances in which this model is appropriate. For example, you might be building a non-linear data structure from the file content. Or you might need to see the last line before you can modify earlier lines (and be unable to re-open the data source from the start).
However I'd suggest a method that's more thrifty with memory. You don't need to keep all those lines in memory. You can read one line, fix it up, then forget about it. But to do this, you'll need to write to a second file.
String filein = "inputfile";
String fileout = filein + ".tmp";
try(
BufferedReader reader = new BufferedReader(new FileReader(filein));
Writer writer = new BufferedWriter(FileWriter(fileout))
) {
while ((String line = bufferedReader.readLine()) != null) {
writer.write(line.replace("þ", "t");
}
}
Files.move(Paths.get(fileout)),
Paths.get(filein),
CopyOption.REPLACE_EXISTING);
I have left out the necessary exception catching -- add back in as required.

File Writer that puts a number of a line before the line it's about to write

I am writing a method for my java class. it looks like this so far:
String file_name;
String line;
void addLine(file_name, line){
int line_number;
try {
FileWriter writer = new FileWriter(file_name, true);
PrintWriter out = new PrintWriter(writer);
out.println(line_number + line);
}
catch (IOException e){
System.out.println(e);
}
}
How should I define line_number so it would check how many lines were there in file before I printed out next into it?

int totalLines = 0;
BufferedReader br br = new BufferedReader(new FileReader("C:\\filename.txt"));
String CurrentLine = "";
while ((CurrentLine = br.readLine()) != null) {
++totalLines
}
i think you have to actually read the file by using a bufferedreader. and then keep on incrementing the totalLines till it reach the end of the file

You can count them with a function posted here: Number of lines in a file in Java
They tested it with a 150 MB log file and it seems to be fast.

Writing with a PrintWriter to a file doesn't come out right

public static void doubleSpace(String fileName) {
try {
FileReader reader = new FileReader(fileName);
Scanner in = new Scanner(reader);
String outputFileName = fileName.charAt(0) + ".ds";
PrintWriter pOut = new PrintWriter(outputFileName);
// Opening of files for input and output
while (in.hasNextLine()) {
String line = in.nextLine();
pOut.println(line + "\n");
pOut.print("\n");
// System.out.println(line + "\n"); //Test
}
pOut.close(); // Close the files if they have been opened.
} catch (Exception e) {
}
}
So basically my input file contains
a
b
c
and my output file should look like
a
b
c
However, my output file always contains only abc.
Any help would be much appreciated!

Use a BufferedWriter. It has a .newLine() method. This method will use the platform's default line separator.
And use a BufferedReader. It has a .readLine() method.
Example:
// NOTE: you should really be using UTF-8
final Charset charset = Charset.defaultCharset();
final Path src = Paths.get(filename);
final Path dst = Paths.get(filename + ".ds");
String line;
try (
final BufferedReader reader = Files.newBufferedReader(src, charset);
final BufferedWriter writer = Files.newBufferedWriter(dst, charset);
) {
while ((line = reader.readLine()) != null) {
writer.write(line);
writer.newLine();
writer.newLine();
}
}

You are likely useing the wrong character(s) for new line for your plattform. Use
System.getProperty("line.separator");
to get the right value.

Removing column names while reading content through Inputstream in Java

I have been trying to remove the column names that come when I read the content of the response returned by http get.
Initially I used http get to get a content and then I read this content using InputStream and then write to local disk as a csv file using FileOutputStream:
InputStream read_content = result.getEntity().getContent();
FileOutputStream writ = new FileOutputStream(new File(path));
byte[] buff = new byte[4096];
int length;
while ((length = read_content.read(buff)) > 0) {
writ.write(buff, 0, length);
}
Here result is the response I get from http get. This works fine but the problem is that the response also contains column names which I want to remove.
After some modification I am using this code now but the output is not coming right:
InputStream read_content = result.getEntity().getContent();
BufferedReader reader =
new BufferedReader(new InputStreamReader(read_content));
FileWriter fstream = new FileWriter(path);
BufferedWriter out = new BufferedWriter(fstream);
reader.readLine();
while (reader.readLine() != null) {
out.write(reader.read());
}
When I execute this modified code then I get garbage result. What am I doing wrong here and how can I remove the table column names?

Yout code should be something like this
BufferedReader br = null ;
BufferedWriter out = null;
try{
InputStream is = new FileInputStream(new File("C:/Space/ConnTest/Test/input.txt"));
br = new BufferedReader(new InputStreamReader(is));
out = new BufferedWriter(new FileWriter(new File("C:/Space/ConnTest/Test/output.txt")));
System.out.println("This is first line ---"+br.readLine());
String str = "";
while ((str = br.readLine()) != null) {
out.write(str);
}
System.out.println("Success");
}
catch(Exception e )
{
e.printStackTrace();
}
finally
{
if(br!=null)
{
br.close();
}
if(out!=null)
{
out.close();
}
}
Dont be confuse with whole code I just replaced your out.write(reader.read()); with
while ((str = br.readLine()) != null) {
out.write(str);
}
And I am calling br.readLine() in SYSOUT so headers will get skipped. Then I am writing the file with br.readLine()

If it's a line, and so is the rest of the content, use BufferedReader.readLine(), and skip the first line.

Java - how to read from file when I used PrintWriter, BufferedWriter and FileWriter to write?

I have method which writes some data to file. I use PrintWriter, BufferedWriter and FileWriter as shown below
public void writeToFile(String FileName){
PrintWriter pw = null;
try {
pw = new PrintWriter(new BufferedWriter(new FileWriter(FileName)));
for(Cars car : list){
pw.println(car.getType());
pw.println(car.getMaxSpeed());
pw.println(car.getOwner());
pw.println();
pw.flush();
}
pw.close();
}
catch(IOException ex){
System.err.println(ex);
}
}
Now how can I read this data from file? I tried to use InputStreamReader, BufferedReader and FileInputStream, but my NetBeans shows me an error message
public void readFromFile() throws IOException {
InputStreamReader fr = null;
try {
fr = new InputStreamReader(new BufferedReader(new FileInputStream(new FileReader("c:\\cars.txt"))));
System.out.println(fr.read());
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
fr.close();
}
}
What is wrong with this method?

BufferedReader in = new BufferedReader(new FileReader("file.in"));
BufferedWriter out = new BufferedWriter(new FileWriter("file.out"));
String line = in.readLine(); // <-- read whole line
StringTokenizer tk = new StringTokenizer(line);
int a = Integer.parseInt(tk.nextToken()); // <-- read single word on line and parse to int
out.write(""+a);
out.flush();

There are several problems in your code :
1) An InputStreamReader takes an InputStream as an argument not a Reader. See http://docs.oracle.com/javase/6/docs/api/java/io/InputStreamReader.html.
2) The FileInputStream does not accept a Reader as argument as well (it takes a File, a FileDescriptor, or a String). See : http://docs.oracle.com/javase/6/docs/api/java/io/FileInputStream.html
3) A BufferedReader reads the File line by line normally. The read() method only reads a single character.
A possible solution could be :
fr = new BufferedReader(new InputStreamReader(new FileInputStream(new File("c:\\cars.txt"))));
String line = "";
while((line = fr.readLine()) != null) {
System.out.println(line);
}
Btw : It would be easier for others to help you, if you provide the exact error-message or even better the StackTrace.

Simple error: Cannot resolve constructor 'FileInputStream(java.io.FileReader)', required constructor not exist in API.
Your original code was:
new PrintWriter(new BufferedWriter(new FileWriter(FileName)));
so for reading, you need
new PrintReader(new BufferedReader(new FileReader(FileName)));
but PrintReader is not needed (not exist), so all you need is:
new BufferedReader(new FileReader(FileName))
PrinterWriter prints formatted representations of objects to a text-output stream, but when reading text is always formatted, so PrinterReader not exist.
You are writing line by line, so also read line by line :) Example:
public void readFromFile() throws IOException {
BufferedReader bufferedReader = null;
try {
String sCurrentLine;
bufferedReader = new BufferedReader(new FileReader("c:\\cars.txt"));
while ((sCurrentLine = bufferedReader.readLine()) != null) {
System.out.println(sCurrentLine);
}
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
bufferedReader.close();
}
}
or better (JDK7)
void readFromFile() throws IOException {
Path path = Paths.get("c:\\cars.txt");
try (BufferedReader reader = Files.newBufferedReader(path, Charset.defaultCharset())){
String line = null;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
}
}