Read and write data in the same txt file

gani

hii,

Greetings,

i am beginner for processing , i stuck in between please help me out,

what i want to do *open a file(xyz.txt) read data from it *do some activity(addition,mltiplication...etc) by that data upgrade it *and store in samefile(xyz.txt)

thank you
:)gani

koogs

STOP SHOUTING we can read lower case...

don't do this. read the first file, write to a second file and then rename the second file to the first file.

gani

oops:( sorry can u help me with a example?

koogs

what do you already have?

gani

To read a data from txt file

i am using this code

                    BufferedReader reader;
                    String line;

                    void setup() {
                      // Open the file from the createWriter() example
                      reader = createReader("positions.txt");
                    }

                    void draw() {
                      try {
                        line = reader.readLine();
                      } 
                      catch (IOException e) {
                        e.printStackTrace();
                        line = null;
                      }
                      if (line == null) {
                        // Stop reading because of an error or file is empty
                        noLoop();
                      } else {
                        String[] lines = loadStrings("positions.txt");
                        println("there are " + lines.length + " lines");
                        for (int i = 0; i < lines.length; i++) {
                          println(lines[i]);
                        }
                      }
                    } 

---

to write data in txt file

i am using this code

        PrintWriter output;
        int i=0;
        void setup() {
          // Create a new file in the sketch directory
          output = createWriter("positions.txt"); 
        }

        void draw() {
          point(mouseX, mouseY);
           // Write the coordinate to the file
        }

        void keyPressed() {

          if(key=='a' || key=='A'){
          output.println("hiii"+i);// Finishes the file
         i++;
          output.flush(); // Writes the remaining data to the file
          output.close(); }
        }

koogs

you don't need a createReader if you use loadStrings() - loadStrings load all the file in one go, createReader is designed for reading a line at a time - two different things. decide which you want.

https://processing.org/reference/createReader_.html

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