Delete Specific Line From Java Text File?

Read file from stream and write it to another stream and skip the line which you want to delete

There is no magic to removing lines.

• Copy the file line by line, without the line you don't want.
• Delete the original file.
• rename the copy as the original file.

Try this code.

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;


class Solution {
    public static void main(String[] args) throws FileNotFoundException, IOException{

        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 + System.getProperty("line.separator"));
        }
        writer.close(); 
        reader.close(); 
        boolean successful = tempFile.renameTo(inputFile);
        System.out.println(successful);

    }
}

Try to read file:

 public static String readAllText(String filename) throws Exception {
    StringBuilder sb = new StringBuilder();
    Files.lines(Paths.get(filename)).forEach(sb::append);
    return sb.toString();
}

then split text from specific character (for new line "\n")

private String changeFile(){
String file = readAllText("file1.txt"); 
String[] arr = file.split("\n"); // every arr items is a line now.
StringBuilder sb = new StringBuilder();
for(String s : arr)
{
   if(s.contains("characterfromlinewillbedeleted"))
   continue;
   sb.append(s); //If you want to split with new lines you can use sb.append(s + "\n");
}
return sb.toString(); //new file that does not contains that lines.
}

then write this file's string to new file with:

public static void writeAllText(String text, String fileout) {
    try {
        PrintWriter pw = new PrintWriter(fileout);
        pw.print(text);
        pw.close();
    } catch (Exception e) {
        //handle exception here
    }
}


writeAllText(changeFile(),"newfilename.txt");

Deleting a text line directly in a file is not possible. We have to read the file into memory, remove the text line and rewrite the edited content.

Maybe a search method would do what you want i.e. "search" method takes a string as a parameter and search for it into the file and replace the line contains that string.

PS:

public static void search (String s)
{
    String buffer = "";
    try {

        Scanner scan = new Scanner (new File ("filename.txt"));
        while (scan.hasNext())
        {
            buffer = scan.nextLine();

            String [] splittedLine = buffer.split(" ");
            if (splittedLine[0].equals(s))
            {

                buffer = "";

            }
            else
            {
                //print some message that tells you that the string not found


            }
        }
        scan.close();

    } catch (FileNotFoundException e) {
        System.out.println("An error occured while searching in file!");
    }

}