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Remove a Specific Line From text file

I trying to remove a specific line from a file. But I have a problem in deleting a particular line from the text file. Let's said, my text file I want to remove Blueberry in the file following:
Old List Text file:
Chocolate
Strawberry
Blueberry
Mango
New List Text file:
Chocolate
Strawberry
Mango
I tried to run my Java program, when I input for delete and it didn't remove the line from the text file.
Output:
Please delete:
d
Blueberry
Remove:Blueberry
When I open my text file, it keep on looping with the word "Blueberry" only.
Text file:
Blueberry
Blueberry
Blueberry
Blueberry
Blueberry
Blueberry
Blueberry
Blueberry
My question is how to delete the specific line from the text file?
Here is my Java code:
String input="Please delete: ";
System.out.println(input);
try
{
BufferedReader reader = new BufferedReader
(new InputStreamReader (System.in));
line = reader.readLine();
String inFile="list.txt";
String line = "";
while(!line.equals("x"))
{
switch(line)
{
case "d":
line = reader.readLine();
System.out.println("Remove: " + line);
String lineToRemove="";
FileWriter removeLine=new FileWriter(inFile);
BufferedWriter change=new BufferedWriter(removeLine);
PrintWriter replace=new PrintWriter(change);
while (line != null) {
if (!line.trim().equals(lineToRemove))
{
replace.println(line);
replace.flush();
}
}
replace.close();
change.close();
break;
}
System.out.println(input);
line = reader.readLine();
}
}
catch(Exception e){
System.out.println("Error!");
}

Let's take a quick look at your code...
line = reader.readLine();
//...
while (line != null) {
if (!line.trim().equals(lineToRemove))
{
replace.println(line);
replace.flush();
}
}
Basically, you read the first line of the file and then repeatedly compare it with the lineToRemove, forever. This loop is never going to exit
This is a proof of concept, you will need to modify it to your needs.
Basically, what you need to ensure you're doing, is you're reading each line of the input file until there are no more lines
// All the important information
String inputFileName = "...";
String outputFileName = "...";
String lineToRemove = "...";
// The traps any possible read/write exceptions which might occur
try {
File inputFile = new File(inputFileName);
File outputFile = new File(outputFileName);
// Open the reader/writer, this ensure that's encapsulated
// in a try-with-resource block, automatically closing
// the resources regardless of how the block exists
try (BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile))) {
// Read each line from the reader and compare it with
// with the line to remove and write if required
String line = null;
while ((line = reader.readLine()) != null) {
if (!line.equals(lineToRemove)) {
writer.write(line);
writer.newLine();
}
}
}
// This is some magic, because of the compounding try blocks
// this section will only be called if the above try block
// exited without throwing an exception, so we're now safe
// to update the input file
// If you want two files at the end of his process, don't do
// this, this assumes you want to update and replace the
// original file
// Delete the original file, you might consider renaming it
// to some backup file
if (inputFile.delete()) {
// Rename the output file to the input file
if (!outputFile.renameTo(inputFile)) {
throw new IOException("Could not rename " + outputFileName + " to " + inputFileName);
}
} else {
throw new IOException("Could not delete original input file " + inputFileName);
}
} catch (IOException ex) {
// Handle any exceptions
ex.printStackTrace();
}
Have a look at Basic I/O and The try-with-resources Statement for some more details

Reading input from console, reading file and writing to a file needs to be distinguished and done separately. you can not read and write file at the same time. you are not even reading your file. you are just comparing your console input indefinitely in your while loop.In fact, you are not even setting your lineTobeRemoved to the input line. Here is one way of doing it.
Algorithm:
Read the console input (your line to delete) then start reading the file and looking for line to delete by comparing it with your input line. if the lines do not match match then store the read line in a variable otherwise throw this line since you want to delete it.
Once finished reading, start writing the stored lines on the file. Now you will have updated file with one line removed.
public static void main(String args[]) {
String input = "Please delete: ";
System.out.println(input);
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
System.in));
String line = reader.readLine();
reader.close();
String inFile = "list.txt";
System.out.println("Remove: " + line);
String lineToRemove = line;
StringBuffer newContent = new StringBuffer();
BufferedReader br = new BufferedReader(new FileReader(inFile));
while ((line = br.readLine()) != null) {
if (!line.trim().equals(lineToRemove)) {
newContent.append(line);
newContent.append("\n"); // new line
}
}
br.close();
FileWriter removeLine = new FileWriter(inFile);
BufferedWriter change = new BufferedWriter(removeLine);
PrintWriter replace = new PrintWriter(change);
replace.write(newContent.toString());
replace.close();
}
catch (Exception e) {
e.printStackTrace();
}
}

How to delete a line from text line by id java

How to delete a line from a text file java?
I searched everywhere and even though I can't find a way to delete a line.
I have the text file: a.txt
1, Anaa, 23
4, Mary, 3
and the function taken from internet:
public void removeLineFromFile(Long id){
try{
File inputFile = new File(fileName);
File tempFile = new File("C:\\Users\\...myTempFile.txt");
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String lineToRemove = Objects.toString(id,null);
String currentLine;
while((currentLine = reader.readLine()) != null) {
// trim newline when comparing with lineToRemove
String trimmedLine = currentLine.trim();
String trimmLine[] = trimmedLine.split(" ");
if(!trimmLine.equals(lineToRemove)) {
writer.write(currentLine + System.getProperty("line.separator"));
}
}
writer.close();
reader.close();
boolean successful = tempFile.renameTo(inputFile);
}catch (IOException e){
e.printStackTrace();
}
}
where the fileName is the path for a.txt.
I have to delete the line enetering the id.That's why I split the trimmedLine. At the end of execution I have 2 files, the a.txt and myTempFile both having the same lines(the ones from beginning). Why couldn't delete it?

If I understand your question correctly, you want to delete the line whose id matches with the id passed in the removeLineFromFile method.
To make your code work, only few changes are needed.
To extract the id, you need to split using both " " and ","
i.e.
String trimmLine[] = trimmedLine.split(" |,");
where | is the regex OR operator.
See Java: use split() with multiple delimiters.
Also, trimmLine is an array, you can't just compare trimmLine with lineToRemove. You first need to extract the first part which is the id from trimmLine. I would suggest you to look at the working of split method if you have difficulty in understanding this. You can have a look at How to split a string in Java.
So, extract the id which is the first index of the array trimmLine here using:
String part1 = trimmLine[0];
and then compare part1 with lineToRemove.
Whole code looks like:
public void removeLineFromFile(Long id){
try{
File inputFile = new File(fileName);
File tempFile = new File("C:\\Users\\...myTempFile.txt");
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String lineToRemove = Objects.toString(id,null);
String currentLine;
while((currentLine = reader.readLine()) != null) {
// trim newline when comparing with lineToRemove
String trimmedLine = currentLine.trim();
String trimmLine[] = trimmedLine.split(" |,");
String part1 = trimmLine[0];
if(!part1.equals(lineToRemove)) {
writer.write(currentLine + System.getProperty("line.separator"));
}
}
writer.close();
reader.close();
boolean successful = tempFile.renameTo(inputFile);
}catch (IOException e){
e.printStackTrace();
}
}

How to edit parts of a line in a text file in java

I'm trying to delete the last four characters of all the lines in a text file. Let's say I have domain.txt and the content:
123.com
student.com
tech.net
running into hundreds of lines. How do I delete the last four characters (the extensions) to remain:
123
student
tech
etc.

I hope this helps.
UPDATED
String a ="123.com";
System.out.println(a.substring(0, a.lastIndexOf(".")));

You can do as below :
File file = new File("file.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = "",
newtext = "";
while((line = reader.readLine()) != null) {
line=line.substring(0, line.lastIndexOf("."))
newtext += line + "\n";
}
reader.close();
// Now write new Content
FileWriter writer = new FileWriter("file.txt");
writer.write(newtext);
writer.close();
Do not forget to use try..catch

Remove a line in a text if

Hi my problem is that I have a text with something like :
something1
[ something2
something3
[ something4
I want to write a code in java that reads that text and search for a character, in this case "[", when it finds it, remove the entire line, in this case "[ something2" , and then keep searching for that character so in the end I will be having something like this
something1
something3
I already search for something like this and I find this approach
File inputFile = new File("myFile.txt");
File tempFile = new File("myTempFile.txt");
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String lineToRemove = "bbb";
String currentLine;
while((currentLine = reader.readLine()) != null) {
// trim newline when comparing with lineToRemove
String trimmedLine = currentLine.trim();
if(trimmedLine.equals(lineToRemove)) continue;
writer.write(currentLine);
}
boolean successful = tempFile.renameTo(inputFile);
That code removes the entire line that haves in it "bbb", the problem here is that erases only the line that has in it only and elusively bbb
by example
something1
bbb
something3
bbb something
after run the code we have
something1
something3
bbb something
so I tried to modify the code to search for the character [ and then erases the entire line.
but I couldn't, so I was hopping that someone could help me.

Try this:
File inputFile = new File("myFile.txt");
File tempFile = new File("myTempFile.txt");
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String lineToRemove = "bbb";
String currentLine;
while((currentLine = reader.readLine()) != null) {
// trim newline when comparing with lineToRemove
String trimmedLine = currentLine.trim();
if(!trimmedLine.contains(lineToRemove))
{
writer.write(currentLine);
}
}
boolean successful = tempFile.renameTo(inputFile);

that code removes the entire line that haves in it "bbb", the problem here is that erases only the line that has in it only and elusively bbb by example
COZ of if(trimmedLine.equals(lineToRemove)) continue;
"bbb something".equals("bbb") returns false and so the line is not skipped
Use regex or String.startsWith() or String.contains() method
Try the following:
if(trimmedLine.contains(lineToRemove)) continue;
[EDIT]
What I recommend is to implement KMP [1] in java (Pattern Matching). Will help you in future.
[1] http://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm

You don't need to write a Java program for this. Chances are you have an OS that knows tools like grep, awk, perl. For example
grep -v '^\[' infile >outfile
will copy the lines you want from file infile to outfile

You should use the contains method.
while((currentLine = reader.readLine()) != null) {
// CHANGED EQUALS TO CONTAINS
if(trimmedLine.contains(lineToRemove)) continue;
writer.write(currentLine);
}
Good luck!

Remove a line in text file with java.BufferedReader

How can I remove or trim a line in a text file in Java?
This is my program but it does not work.
I want to remove a line in text file, a line contain the word of user input
try {
File inputFile = new File("temp.txt");
File tempFile = new File("temp1.txt");
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String lineToRemove = name;
String currentLine;
while((currentLine = reader.readLine()) != null)
{
//trim newline when comparing with lineToRemove
String trimmedLine = currentLine.trim();
if(!trimmedLine.startsWith(lineToRemove))
{
// if current line not start with lineToRemove then write to file
writer.write(currentLine);
}
}
writer.close();
reader.close();
}
catch(IOException ex)
{
System.out.println("Error reading to file '" + fileName + "'");
}

You are not separating the lines with a line break character, so the resulting file will have one single long line. One possible way to fix that is just writing the line separator after each line.
Another possible problem is that you are only checking if the current line starts with the given string. If you want to check if the line contains the string you should use the contains method.
A third problem is that you are not writing the trimmed line, but the line as it is. You really don't say what you expect from the program, but if you are supposed to output trimmed lines it should look like this:
if(!trimmedLine.contains(lineToRemove)) {
writer.write(trimmedLine);
writer.newLine();
}

startsWith() is the culprit. You are checking if the line starts with "lineToRemove". As #Joni suggested use contains.