Android Not Saving Files

Question

I've been doing some work in Android, and I've found after three or four different attempts, I can't seem to get Android to save my file anywhere. In fact, it doesn't even create a folder in data/ for my app.

Here's how I'm trying to save the file - this is in my main activity also.

@Override
public void onStop(){
    super.onStop();

    try{
        FileOutputStream memboricOut = getApplicationContext().openFileOutput("memboric.core", Context.MODE_PRIVATE);
        brain.save(memboricOut);
    }catch(Exception e){
        System.err.println("Could not save memboric core.");
        e.printStackTrace();
    }
}

And inside brain.save():

public boolean save(FileOutputStream fileOut) {
    try{
        ObjectOutputStream oo = new ObjectOutputStream(fileOut);
        oo.writeObject(this);
        oo.close();
        fileOut.close();
        System.out.println("Memboric Core saved successfully.");
        return true;
    }catch (Exception e) {
        e.printStackTrace();
    }

    return false;
}

This code seems to do nothing. I've also placed the saving in onDestroy as well.

Have I just chosen bad placement for the saving? I can't imagine what could possibly being going wrong.

Answer 1

Do you have the permission to save files ? You can add that by adding android.permission.WRITE_EXTERNAL_STORAGE permission to you AnroidManifest.xml.

Answer 2

oo.writeObject(this);

Is brain have serializable data?

Class Brain implements java.io.Serializable {
    public String toString() {
        return "serialized data";
    }
}

If not, DataOutputStream maybe a better choice.

DataOutputStream oo = new DataOutputStream(fileOut);
oo.writeInt(value); // if breain have int value
oo.flush();
oo.close();

Saved data will be appear in /data/data/(your.package.name)/files/memboric.core
Check the file with emulator (or rooted device).