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How to replace a word from txt file with regular expression in java

I want to replace a word from a txt file in java. I already have my regular expression and the method for reading the txt file from java. But i have no idea how to replace a word from it using mu regualar expression.
Any suggestion or example?

public class BTest
{
public static void main(String args[])
{
try
{
File file = new File("file.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = "", oldtext = "";
while((line = reader.readLine()) != null)
{
oldtext += line + "\r\n";
}
reader.close();
// replace a word in a file
String newtext = oldtext.replaceAll("drink", "Love");
//To replace a line in a file
//String newtext = oldtext.replaceAll("This is test string 20000", "blah blah blah");
FileWriter writer = new FileWriter("file.txt");
writer.write(newtext);writer.close();
}
catch (IOException ioe)
{
ioe.printStackTrace();
}
}
}

Parse the file into one string.Then replace all instances of word with new word.
String response = "test string".replaceAll("regex here", "new text");
Then write the new text to a file
FileWriter writer = new FileWriter("out.txt");
writer.write(response);

I am using the epublib and I am trying to get the entire chapter of a book at a time

I am trying to get one chapter at a time of a book. I am using the Paul Seigmann library. However, I am not sure how to do it but I am able to get all the text from the book. Not sure where to go from there.
// find InputStream for book
InputStream epubInputStream = assetManager
.open("the_planet_mappers.epub");
// Load Book from inputStream
mThePlanetMappersBookEpubLib = (new EpubReader()).readEpub(epubInputStream);
Spine spine = new Spine(mThePlanetMappersBookEpubLib.getTableOfContents());
for (SpineReference bookSection : spine.getSpineReferences()) {
Resource res = bookSection.getResource();
try {
InputStream is = res.getInputStream();
BufferedReader r = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = r.readLine()) != null) {
line = Html.fromHtml(line).toString();
Log.i("Read it ", line);
mEntireBook.append(line);
}
} catch (IOException e) {
}

I don't know if you're still looking for an answer, but...
I'm working on it too right now. This is the code I have to retrieve the content of all the epub file:
public ArrayList<String> getBookContent(Book bi) {
// GET THE CONTENTS OF ALL PAGES
StringBuilder string = new StringBuilder();
ArrayList<String> listOfPages = new ArrayList<>();
Resource res;
InputStream is;
BufferedReader reader;
String line;
Spine spine = bi.getSpine();
for (int i = 0; spine.size() > i; i++) {
res = spine.getResource(i);
try {
is = res.getInputStream();
reader = new BufferedReader(new InputStreamReader(is));
while ((line = reader.readLine()) != null) {
// FIRST PAGE LINE -> <?xml version="1.0" encoding="utf-8" standalone="no"?>
if (line.contains("<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>")) {
string.delete(0, string.length());
}
// ADD THAT LINE TO THE FINAL STRING REMOVING ALL THE HTML
string.append(Html.fromHtml(formatLine(line)));
// LAST PAGE LINE -> </html>
if (line.contains("</html>")) {
listOfPages.add(string.toString());
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
return listOfPages;
}
private String formatLine(String line) {
if (line.contains("http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd")) {
line = line.substring(line.indexOf(">") + 1, line.length());
}
// REMOVE STYLES AND COMMENTS IN HTML
if ((line.contains("{") && line.contains("}"))
|| ((line.contains("/*")) && line.contains("*/"))
|| (line.contains("<!--") && line.contains("-->"))) {
line = line.substring(line.length());
}
return line;
}
As you may have notice I need to improve the filter, but I have every chapter of that book in my ArrayList. Now I just need to call that ArrayList like myList.get(0); and is done.
To show the text in a proper way, I'm using the bluejamesbond:textjustify library (https://github.com/bluejamesbond/TextJustify-Android).
It is easy to use and powerful.
I hope it helps you, and if anybody finds a better way to filter that html, notice me, please.

Replace a String inside a file using java

I have a TXT file in which I'd like to change this String
<!DOCTYPE Publisher
PUBLIC "-//Springer-Verlag//DTD A++ V2.4//EN" "http://devel.springer.de/A++/V2.4/DTD/A++V2.4.dtd">
into this one <!DOCTYPE Publisher> using Java.
I wrote the following function but it seems not to be working.
public void replace() {
try {
File file = new File("/home/zakaria/Bureau/PhD/test2/file.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = "", oldtext = "";
while((line = reader.readLine()) != null) {
oldtext += line + "\n";
}
reader.close();
String newtext = oldtext
.replaceAll("<!DOCTYPE Publisher\nPUBLIC \"-//Springer-Verlag//DTD A++ V2.4//EN\" \"http://devel.springer.de/A++/V2.4/DTD/A++V2.4.dtd\">",
"<!DOCTYPE Publisher>");
FileWriter writer = new FileWriter("/home/zakaria/Bureau/PhD/test2/file.txt");
writer.write(newtext);
writer.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
What did I do wrong?

Try this simple code:
public static void replace() {
try {
File file = new File("resources/abc.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = "", oldtext = "";
boolean found = false;
while ((line = reader.readLine()) != null) {
if (line.trim().startsWith("<!DOCTYPE Publisher")) {
found = true;
}
if (line.trim().endsWith("A++V2.4.dtd\">")) {
oldtext += "<!DOCTYPE Publisher>";
found = false;
continue;
}
if (found) {
continue;
}
oldtext += line + "\n";
}
reader.close();
FileWriter writer = new FileWriter("resources/file.txt");
writer.write(oldtext);
writer.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}

You are fortunate to start with that it didn't change anything at all.
Otherwise you'd have lost your original file...
Never modify a file in place!!
Create a temporary file where you write the modified content, and only then rename to your original file.
Also, the string you want to replace is pretty complicated, and you don't want to use .replace() since this will replace all occurrences.
Do like this:
final String quoted
= Pattern.quote("<!DOCTYPE Publisher\nPUBLIC \"-//Springer-Verlag//DTD A++ V2.4//EN\" \"http://devel.springer.de/A++/V2.4/DTD/A++V2.4.dtd\">");
final Pattern pattern = Pattern.compile(quoted);
final Path victim = Paths.get("/home/zakaria/Bureau/PhD/test2/file.txt");
final Path tmpfile = Files.createTempFile("tmp", "foo");
final byte[] content = Files.readAllBytes(victim);
final String s = new String(content, StandardCharsets.UTF_8);
final String replacement = pattern.matcher(s).replaceFirst("<!DOCTYPE Publisher>");
try (
final OutputStream out = Files.newOutputStream(tmpfile);
) {
out.write(replacement.getBytes(StandardCharsets.UTF_8));
out.flush();
}
Files.move(tmpfile, victim);

If the text you want to eliminate is on the second and subsequent lines, as in your demo-input
<!DOCTYPE Publisher
PUBLIC "-//Springer-Verlag//DTD A++ V2.4//EN"
"http://devel.springer.de/A++/V2.4/DTD/A++V2.4.dtd">
and no lines between the first and last in the tag contain a closing >, then you can do the following:
while(more lines to process)
if "<!DOCTYPE Publisher" is not found
read line and output it
else
//This is the first line in a <!DOCTYPE tag
read the line and output it, appending '>' to the end
while the next line does NOT end with a '>'
discard it (don't output it)

Try with this regexp:
String newtext = oldtext.replaceAll(
"<!DOCTYPE Publisher\nPUBLIC \"-\\/\\/Springer-Verlag\\/\\/DTD A[+][+] V2[.]4\\/\\/EN\"[ ]\"http:\\/\\/devel[.]springer[.]de\\/A[+][+]\\/V2[.]4\\/DTD\\/A[+][+]V2[.]4[.]dtd\">", "<!DOCTYPE Publisher>");
The only changes are escaping forward slashes and putting dots and plus signs between square brackets.

Writing multiple queries from a test file

public static void main(String[] args) {
ArrayList<String> studentTokens = new ArrayList<String>();
ArrayList<String> studentIds = new ArrayList<String>();
try {
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream(new File("file1.txt"));
BufferedReader br = new BufferedReader(new InputStreamReader(fstream, "UTF8"));
String strLine;
// Read File Line By Line
while ((strLine = br.readLine()) != null) {
strLine = strLine.trim();
if ((strLine.length()!=0) && (!strLine.contains("#"))) {
String[] students = strLine.split("\\s+");
studentTokens.add(students[TOKEN_COLUMN]);
studentIds.add(students[STUDENT_ID_COLUMN]);
}
}
for (int i=0; i<studentIds.size();i++) {
File file = new File("query.txt"); // The path of the textfile that will be converted to csv for upload
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = "", oldtext = "";
while ((line = reader.readLine()) != null) {
oldtext += line + "\r\n";
}
reader.close();
String newtext = oldtext.replace("sanid", studentIds.get(i)).replace("salabel",studentTokens.get(i)); // Here the name "sanket" will be replaced by the current time stamp
FileWriter writer = new FileWriter("final.txt",true);
writer.write(newtext);
writer.close();
}
fstream.close();
br.close();
System.out.println("Done!!");
} catch (Exception e) {
e.printStackTrace();
System.err.println("Error: " + e.getMessage());
}
}
The above code of mine reads data from a text file and query is a file that has a query in which 2 places "sanid" and "salabel" are replaced by the content of string array and writes another file final . But when i run the code the the final does not have the queries. but while debugging it shows that all the values are replaced properly.

but while debugging it shows that all the values are replaced properly
If the values are found to be replaced when you debugged the code, but they are missing in the file, I would suggest that you flush the output stream. You are closing the FileWriter without calling flush(). The close() method delegates its call to the underlying StreamEncoder which does not flush the stream either.
public void close() throws IOException {
se.close();
}
Try this
writer.flush();
writer.close();
That should do it.

check if a value exists in an external file (java)

Is it possible (and wise) to check if a value exists in an external text file.
So if i have a file: bankcodes.txt that contains the next lines:
INGB
ABNA
...
Is it possible to check if a value is present in this file?
The reason is that these values can change and need to be easily changed whitout making a new jar file.
If there is another, wiser way of doing this i would like to hear it too.

From here:
https://stackoverflow.com/a/4716623/110933
Read contents of file line by line and check the value you get for "line" for the value you want:
BufferedReader br = new BufferedReader(new FileReader("file.txt"));
try {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append("\n");
line = br.readLine();
}
String everything = sb.toString();
} finally {
br.close();
}

Give example how i did it , while File.txt -> our text and ourValue it the one we searching
String ourValue="value"
BufferedReader br = new BufferedReader(new FileReader("File.txt"));
String line = br.readLine();
boolean exist = false;
while (line != null&&!exist) {
if (ourValue.equals(line)) {
exist = true;
} else {
line = br.readLine();
}
}
System.out.println("the value " +ourValue+" exist in the Text? "+ exist);
}