How Can I Efficiently Remove Specific Lines from a Text File Using Programming?

Removing Lines from Text Files

When working with large text files, it is often necessary to remove certain lines to clean up the data or organize the file. This can be done efficiently using programming techniques.

Finding and Eliminating Specific Lines

Suppose you have a text file containing the following content:

myFile.txt:
aaa
bbb
ccc
ddd

Your goal is to create a function called removeLine(String lineContent) that takes a line as input and removes that line from the file. Passing removeLine("bbb") should result in the following updated file:

myFile.txt
aaa
ccc
ddd

Solution Using File I/O

One approach to remove lines from a file is to read it line by line and write the lines that do not match the specified line content to a temporary file. Once all lines have been processed, rename the temporary file to replace the original.

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) {
    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);

This solution ensures that the original file is not modified until the changes are complete, thereby preventing any potential data loss.

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