reading and writing to the same file

Android Processing

David Wil..

reading and writing to the same file

in Android Processing • 2 years ago

Hi,

Can anyone tell me how to go about reading and writing to the same file in Android mode?

My sketch runs perfectly in 'normal' mode, periodically reading from, and overwriting a text file. But, in Android mode it appears the text file needs to be moved into the "data" folder in order to be located - This leaves me unable to overwrite it as saveStrings() outputs to the main sketch folder? I've tried adding a path:

saveStrings("data/alpine.txt", levelData);

and got the following error when launching on the AVD :

java.lang.IllegalArgumentException: File data/alpine.txt contains a path separator

Help appreciated

Dave

Replies(9)

ckamath

Re: reading and writing to the same file

2 years ago

I am not a pro at programming but this is what worked for me: The following code snippet creates a new file called "Player_Data.txt" on the phone if not existent previously

void check_file()
{
if((new File("/data/data/processing.android.test.<sketchname>/files/Player_Data.txt")).exists()){
    println("User file exists");
    try{
      user_data = new FileWriter("/data/data/processing.android.test.<sketchname>/files/Player_Data.txt", true);
      bw = new BufferedWriter(user_data);
      exists_flag = true;
    }catch(IOException e){
      println("Exception at existing file edit: "+e);
      exists_flag = false;
    }
}else{
    try{
      user_data = new FileWriter("/data/data/processing.android.test.flakefrenzy/files/Player_Data.txt");
      exists_flag = true;
    }catch(IOException e){
      println("Exception at new file creation: "+e);
      exists_flag = false;
    }
    if(exists_flag){
      println("Creating new player file: "+user_data);
      check_file();
    }
}
}

Then, you can read the file using:

void read_file()
{
   try
{
     fro = new FileReader( "/data/data/processing.android.test.flakefrenzy/files/Player_Data.txt" );
     bro = new BufferedReader( fro );

     // declare String variable and prime the read
     String stringRead = bro.readLine( );

      while( stringRead != null ) // end of the file
     {
         println(stringRead)
        stringRead = bro.readLine( ); // read next line
     }

     bro.close( );

}

Then you can write using:

void write_file(String lines)
{
try{
    bw.write(lines);
    bw.newLine();
    bw.flush();
}catch(IOException e)
{
    println("Exception at write file: "+e);
}
}

This file once created will always stay on your phone until you uninstall the application or clear data from setting-applications menu. This is a good thing as it's what is needed in games and high scores.

Hope this helps. Let me know if it worked or just crashed

David Wil..

Re: reading and writing to the same file

2 years ago

Few tweaks and it works like a charm, thanks for your help.

darkgisba

Re: reading and writing to the same file

2 years ago

David , coul you be specific about what tweaks you did? because im trying to get the same snipet of code to work but to no avail.

Also if anyone finds a quicker and cleaner aproach to save/load files on android please say something ;)

David Wil..

Re: reading and writing to the same file

2 years ago

You need to declare your own FileReader and Buffered Reader and also a boolean to say if the data exists, also println(stringRead) needs a ; on the end. You also need to modify the path so that it works for your sketch.

Hope this helps

Dave

darkgisba

Re: reading and writing to the same file

2 years ago

ill get back to you on that later tonight , regardless , thanks for the help!

David Wil..

Re: reading and writing to the same file

2 years ago

Anytime.

darkgisba

Re: reading and writing to the same file

2 years ago

Actually I have to ask something.

What do you declare them as?

I supose I need to declare FileWriter and bufferedWriter aswell.

Im still pretty much a begginer with classes (object oriented programming), do I need to declare all those variables above as strings or ?

Sorry for the extremly begginer question :\

David Wil..

Re: reading and writing to the same file

2 years ago

Possibly this isn't for you if you're just getting into classes etc, but either way you'll need to do some reading.

Basically they're just a bunch of objects for handling strings, or streams of data.

FileReader, Buffered Reader, FileWriter and BufferedWriter

darkgisba

Re: reading and writing to the same file

2 years ago

ok everyone , i found a very much simplistic way of doing it and i will share it here;

void saveScore() {
String[] scores = new String[1];
scores[0] = highScore+"";
saveStrings("\\sdcard\\score.txt", scores);
}
void loadScore() {
try {
String[] scores = loadStrings("\\sdcard\\score.txt");
highScore = int(scores[0]);
}
catch (NullPointerException e){
println("shabba");
}
}

This way it loads the score, and if the file hasent been created yet, it skips the error and the game keeps running, after when it saves it, it just saves it to the directory.

The thing with this is , by setting a directory of my own in there it allowed me to write and save directly on the phone because it will save and load from the same directory!