Check if file exists or not

[jensemand]

As the title says, I want to check whether a file exists. I am not trying to look at the data folder because I think you just have to use dataFile().
At the moment I just have to see if a specific file is in the sketch folder.
I have written the following code.

String[] lines1 = loadStrings("positions1.txt"); // file exists or not but you get a 
  if (lines1==null){
    println("nothing is here");
  }

However this returns some sort of error message about the file might not exist (obviously) and if I have to look at over a hundred files it can become quite a lot of error messages.
Is there any simple way to check whether a file exists without getting this kind of error message?

[jafal]

Hi

How to check if a file is exist in data folder by code?

I have to check if a file is exist in data folder while the code is running. How to achieve that function?

[Pieter]

I haven’t checked if this applies in this case, but you may use a try/catch block to discard any thrown exceptions.

Reference

[GoToLoop]

@jensemand

Is there any simple way to check whether a file exists without getting this kind of error message?

Check if (!dataFile(name).isFile()) table = createAndSaveTableFile(name);
at file “Card_Functions.pde” within function loadCards():

The operator > is undefined for the argument - HOW TO RESOLVE ERROR (OOP)

If you wish you can take a look at a very old deck of cards implementation I did a long time ago: Picking cards at random, then excluding those from further picking. - Processing 2.x and 3.x Forum It’s split into 2 sketches: 1 creates & saves the “.csv” file, while the other loads it and makes a deck of cards out of it. For convenience I’ve merged them now into 1 sketch w/ 4 “.pde” tabs: “Table_CSV_Card_Pack.pde”: /** * Table CSV Card Pack (v1.0.1) * by GoToLoop (2022/Sep/13) * * htt…

[jensemand]

Sorry but this didn’t help because when I write the following:

BufferedReader reader;
String line;
boolean stopReading=false;
 
void setup() {
  // Open the file from the createWriter() example
  reader = createReader("positions1.txt");
  while(!stopReading){
    try {
      line = reader.readLine();
    } catch (IOException e) {
      e.printStackTrace();
      line = null;
    }
    if (line == null) {
    // Stop reading because of an error or file is empty
      println("there is no more text");
      stopReading=true;
      noLoop();  
    } else {
      println(line);
    }
  }
}
 
void draw() {
  
}

it gives an nullpointerexception. It does this because I have changed the filename. It would be great if I can just change the filename and either it says there is no text if the file doesn’t exists and print the lines if the file exists

[GoToLoop]

Add if (!dataFile("positions1.txt").isFile()) exit();
before reader = createReader("positions1.txt");

[jensemand]

This just gives me a NullPointerException sadly.

BufferedReader reader;
String line;
boolean stopReading=false;
 
void setup() {
  // Open the file from the createWriter() example
  if (!dataFile("positions1.txt").isFile()) exit();
  reader = createReader("positions1.txt");
  while(!stopReading){
    try {
      line = reader.readLine();
    } catch (IOException e) {
      e.printStackTrace();
      line = null;
    }
    if (line == null) {
    // Stop reading because of an error or file is empty
      println("there is no more text");
      stopReading=true;
      noLoop();  
    } else {
      println(line);
    }
  }
}
 
void draw() {
  
}

The problem seems to be in the catch()-part of the code. I have looked around but I can’t find anything about catching a NullPointerException.