How do I write data to the phone or SD card memory?

Android Processing

sparkyhes..

How do I write data to the phone or SD card memory?

in Android Processing • 1 year ago

I'm want to write an Android app in Processing that records GPS coords to a text file when I press a button on the screen.
I'll be using the coords later in another sketch.
But I can't figure out how to capture a variable to memory that can be accessed later even if the App has been closed down.

Replies(3)

sparkyhes..

Re: How do I write data to the phone or SD card memory?

1 year ago

After a bit of searching around on forums and the internet I've found a solution.
You need to use something called Bufferedwriter to make sure data is added to the file ont he sd card and not over-written.

Code below - comments welcome as always:

/*
Processing for Android code that writes mouse data to a file on the sdcard of the device
Using buffered writer ensures that new values are added to the file instead of over-writing them
Tip: install something like 'Astro' on your android device to make it super easy to find the text file on the SD card
*/

// Android fonts
String[] fontList;
PFont androidFont;
int sh;
int sw;
int mouse_x;

void setup() {
   size(screenWidth, screenHeight, A2D);
sw = screenWidth;
sh = screenHeight;
//size(480, 640, A2D);
// Sketch stays in portrait mode, even when the phone is rotated
orientation(PORTRAIT);
// Select a font to use
fontList = PFont.list();
androidFont = createFont(fontList[0], 26, true);
textFont(androidFont);
}

void draw() {
   background(0);
fill(255);
text(mouse_x,width/2,height/2.5); //display mouse X position on screen
}

void mousePressed() {
mouse_x = mouseX;
background(0);
//write mouseX value to a file on the SD card
try {
    BufferedWriter writer = new BufferedWriter(new FileWriter("//sdcard//datafile.txt", true)); //set up file to write to
    writer.write(mouseX + "\n");

    writer.flush();
    writer.close();
}
catch (IOException ioe) {
    println("error: " + ioe);
}

}

Jesse Sco..

Re: How do I write data to the phone or SD card memory?

1 year ago

Yeah, that's correct...

Here is a function in a project of mine that saves GPS coordinates to file

(full source will be posted soon...)

void saveToFile() {
//println("Saving GPS");
String taggedLocation = tagLocation.getText() + ".3gp";
String currLat = nf(currentLatitude, 2, 4);
String currLon = nf(currentLongitude, 2, 4);
try {
BufferedWriter writer = new BufferedWriter(new FileWriter("//sdcard//SonicDrift//SavedLocations.txt", true));
writer.write(taggedLocation);
writer.write("\n");
writer.write(currLat);
writer.write("\n");
writer.write(currLon);
writer.write("\n");
writer.flush();
writer.close();
println("Saved new file " + taggedLocation);
}
catch (IOException e) {
println("Saving Error... ");
}
}

And in my setup() I do this to check that the directory exists on my SD Card...

// Create Directory
try{
dirName = "//sdcard//SonicDrift";
File newFile = new File(dirName);
newFile.mkdirs();
if(newFile.exists()) {
println("Directory Exists...");
if(newFile.isDirectory()) {
println("isDirectory = true...");
} else println("isDirectory = false...");
} else {
println("Directory Doesn't Exist...");
}
}
catch(Exception e) {
println("Exception creating folder... ");
//e.printStackTrace();
}

All of this code is taken from other examples on the forum here... there are quite a few threads about reading/writing...

PhiLho

Re: How do I write data to the phone or SD card memory?

1 year ago

It can be slightly simpler by using a print writer. See, for example https://forum.processing.org/topic/log-data-on-a-csv-file-is-it-possible That's also an example of correctly closing the writer: if you have an exception, you don't close it. Alas, lot of examples of Java I/O on the Net look like this...

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