How to edit a text file

quasarbright

I have managed to make a simple file writing program which can append to a file. Now, I want to know how to edit an already existing text file. I want to be able to access a specific line or something and then change or append stuff onto that line. How do you do these kinds of things? Here is my code:
import java.io.FileWriter; import java.io.BufferedWriter; void setup() { size(1, 1); try { FileWriter output = new FileWriter(sketchPath()+"\\strings.txt", true); output.write("stuff"); output.write(System.getProperty( "line.separator" )); output.flush(); output.close(); } catch(IOException e) { println("It broke!!!"); e.printStackTrace(); } exit(); }

Lord_of_the_Galaxy

loadStrings()?

Chrisir

Do you mean a text editor like in working wirh cursor and keyboard?

Look at gui libraries

jeremydouglass

@quasarbright -- If you want to write everything in Java using things like java.io.FileWriter then you probably want an approach like this:

• http://stackoverflow.com/questions/20039980/java-replace-line-in-text-file

However, I think that @Lord_of_the_Galaxy has the right recommendation. Use loadStrings() -- then modify a line in memory -- then use saveStrings():

• https://processing.org/reference/loadStrings_.html
• https://processing.org/reference/saveStrings_.html

If you have not already, read the "Manipulating Strings" part of the Data Tutorial:

• https://processing.org/tutorials/data/

To test, create a sketch with a data file list.txt:

lorem
ipsum
dolor
sit
amet

Here is a sketch that loads the lines, replaces one line, modifies another, and saves the results in a new file (or, if you choose, in the same file). All of these operations (and others, including appending or inserting) are operations on a simple array of strings, not file operations.

// load the file
String lines[] = loadStrings("list.txt");
// change a specific line
if(lines.length>1){
  lines[1] = "REPLACED";
}
// find a line and change it
for (int i = 0 ; i < lines.length; i++) {
  if(lines[i].equals("dolor")==true){
    println("true");
    lines[i] = "MODIFIED " + lines[i];
  }
}
// save the file
saveStrings("list-new.txt", lines);
// saveStrings("list.txt", lines);