How do you edit a specific line in a text file in Java?

How do you edit a text line in Java?

Procedure

  1. Instantiate the File class.
  2. Instantiate the Scanner class passing the file as parameter to its constructor.
  3. Create an empty StringBuffer object.
  4. add the contents of the file line by line to the StringBuffer object using the append() method.
  5. Convert the StringBuffer to String using the toString() method.

How do I change one line in a text file?

Logic to replace specific line in a text file

  1. Open source file in read mode, store its reference to fPtr .
  2. Create and open a temporary file with name replace. …
  3. Input line number to replace in file from user. …
  4. Input new line from user to replace with, store it in newline .
  5. Initialize a count variable with 0.

How do you edit a text file in Java?

Modify a . txt file in Java

  1. Open the existing file using a BufferedReader.
  2. Read each line, make modifications to each line, and add it to a StringBuilder.
  3. Once all the text has been read and modified, write the contents of the StringBuilder to a new file.
  4. Replace the old file with the new file.
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How do you delete a specific line from a text file in Java?

private String changeFile(){ String file = readAllText(“file1. txt”); String[] arr = file. split(“n”); // every arr items is a line now.

There is no magic to removing lines.

  1. Copy the file line by line, without the line you don’t want.
  2. Delete the original file.
  3. rename the copy as the original file.

How do you clear a text file in Java?

How to delete a string inside a file(. txt) in java?

  1. Retrieve the contents of the file as a String.
  2. Replace the required word with an empty String using the replaceAll() method.
  3. Rewrite the resultant string into the file again.

How do I change the first line of a file in Java?

First use BufferedReader ‘s readLine() to read the first line. Modify it and write it to the BufferedWriter . Then use a char[] array to perform a brute-force copy of the remainder of the file. This will be more efficient than doing the copy line by line.

How do you edit a text file in Matlab?

Direct link to this answer

  1. fid =fopen(‘your_file.txt’);
  2. C=textscan(fid,’%s’,’delimiter’,’n’);
  3. tmp = regexp(C{1,1}(k),’s’); % find empty spaces.
  4. C{1,1}{k,1}(tmp{1,1}) = ‘,’; % substitute empty spaces by ‘,’
  5. C{1,1}(k) = strcat(‘{‘,C{1,1}(k),’},’); % add brackets.
  6. fName = ‘new_file.txt’;

How do I replace a line in a text file in Matlab?

Direct link to this answer

  1. sed. …
  2. Or you could open the input file, open the output file, copy 68 lines from the input to the output, then read one line from input and write out the replacement output instead of the input line, then read the rest of the lines from input and copy them to output; finally, close both files.
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How do I read a text file in Matlab?

Use fopen to open the file, specify the character encoding, and obtain the fileID value. When you finish reading, close the file by calling fclose(fileID) . A = fscanf( fileID , formatSpec , sizeA ) reads file data into an array, A , with dimensions, sizeA , and positions the file pointer after the last value read.

How do you create a text file in Java?

Write to a Text File in Java

  1. import java.io.FileWriter; …
  2. public WriteFile( String file_path , boolean append_value ) {
  3. path = file_path; …
  4. } …
  5. FileWriter write = new FileWriter( path , append_to_file); …
  6. PrintWriter print_line = new PrintWriter( write ); …
  7. print_line. …
  8. print_line.printf( “%s” + “%n” , textLine);

How do you write to a file in Java?

Java – Write to File

  1. Overview. In this tutorial, we’ll explore different ways to write to a file using Java. …
  2. Write With BufferedWriter. …
  3. Write With PrintWriter. …
  4. Write With FileOutputStream. …
  5. Write With DataOutputStream. …
  6. Write With RandomAccessFile. …
  7. Write With FileChannel. …
  8. Write With Files Class.

What is a file in Java?

Advertisements. Java File class represents the files and directory pathnames in an abstract manner. This class is used for creation of files and directories, file searching, file deletion, etc. The File object represents the actual file/directory on the disk.

How do I remove the first line of a text file in Java?

Scanner fileScanner = new Scanner(myFile); fileScanner. nextLine(); This will return the first line of text from the file and discard it because you don’t store it anywhere.

How do you overwrite a file in Java?

If you write a file in Java which is already present in the location, it will be overwritten automatically. Unless you are writing to that file with an append flag set to True. FileWriter fw = new FileWriter(filename,false); It will overwrite the file i.e. clear the file and write to it again.

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How do you clear the console in Java?

Use ANSI Escape Codes to Clear Console in Java

To clear the console in Java, we will use the escape code 33[H33[2J . This weird set of characters represents the command to clean the console. To understand it better, we can break it down. The first four characters 33 means ESC or the escape character.

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