How to save to File in android programatically

Question

I have been searching the internet to find a resolution to my answer, have gone through all the documentation, and have looked through multiple forums before posting my own question on this. I need to save information through a file because my function

@Override
protected void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putInt("PointCount", pointCount);
    savedInstanceState.putInt("UpOneCost", upOne);
    savedInstanceState.putInt("UpTwoCost", upTwo);
    savedInstanceState.putInt("TimerTime", upgradeTime);
    super.onSaveInstanceState(savedInstanceState);
    Toast.makeText(this, "Saving", Toast.LENGTH_LONG).show();
}

onSaveInstanceState only works at specific intervals at which I'm not entirely clear on. However, I know it doesn't get called when the activity is destroyed. The function above is mySaveInstanceState function and below is my restoreInstanceState function

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    Toast.makeText(this, "Restoring", Toast.LENGTH_LONG).show();
    if(savedInstanceState != null){
        pointCount = savedInstanceState.getInt("PointCount");
        upOne = savedInstanceState.getInt("UpOneCost");
        upTwo = savedInstanceState.getInt("UpTwoCost");
        upgradeTime = savedInstanceState.getInt("TimerTime");
        if(upgradeTime < 5500){
            startTimer();
        }

        TextView pointCountText = (TextView)findViewById(R.id.myTextView1);
        pointCountText.setText("Points: " + Integer.toString(pointCount));

        TextView pointCountText2 = (TextView)findViewById(R.id.upgradeScreenPointText);
        pointCountText2.setText("Points: " + Integer.toString(pointCount));

        Button upButtonOne = (Button)findViewById(R.id.upButton1);
        upButtonOne.setText("Cost: " + Integer.toString(upOne));

        Button upButtonTwo = (Button)findViewById(R.id.upButton2);
        upButtonTwo.setText("Cost: " + Integer.toString(upTwo));

        TextView myTimerValue = (TextView)findViewById(R.id.myTimerValueText);
        myTimerValue.setText("Current Time: " + Integer.toString(upgradeTime));
    }
}

There is a bit of useless info in there but overall this doesn't run when I hit the back button on the android device, so after a bit of research, i decided I should just save it into a file directory. This is where I created a file in my android project file named "saveFile" It is a text file, and it is in the same directory as my mainActivity.java file in order to remove file scope complications. In an effort to reach this file I came to the conclusion of overriding the onDestroy() function and try

String fileName = "saveFile";
FileOutputStream outputStream;

@Override
protected void onDestroy() {
    super.onDestroy();
    outputStream.openFileOutput(fileName, Context.MAKE_PRIVATE);
}

At which point I was already stopped because it couldn't find the file. The documentation is not clear on where this file should go directory wise, and as far as creation and then writing it is also very vague. If anyone could give a very clear explanation as to how all of it works I would be very appreciative of it. Thank you =) Note some of the code may contain minor errors since I typed some of it instead of copy paste but the idea is there. The only error I receive in the editor is on the outputStream.openFileOutput() line, which says it can't find the file.

Answer 1

In order to do file operations you should specify complete file path. Passing only the filename will throw FileNotFoundException.

You can do one of the following; 1. Save the file in app cache. filePath = appContext.getCacheDir( ).getAbsolutePath( )+"yourFileName";

2. Save the file in app data directory. filePath = Environment.getDataDirectory( ).getPath( ) + File.separator + "data" + File.separator + appContext.getPackageName( ) + File.separator+"yourFileName";

3. Save the file in some folder on SD card. File sdCard = Environment.getExternalStorageDirectory( ); String filePath = sdCard.getAbsolutePath( ) + File.separator + BASE_FOLDER_ON_SD_CARD + File.separator+"yourFileName";

For the third option you may need to add WRITE_EXTERNAL_STORAGE permission in AndroidManifest.xml of your application.

Also, saving the file should happen in onStop() method of your activity and reading the file content should happen in onResume() Use the file from stored location.

Answer 2

You can do like this.

private void writeToFile(String data) {
try {
    OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput("config.txt", Context.MODE_PRIVATE));
    outputStreamWriter.write(data);
    outputStreamWriter.close();
}
catch (IOException e) {
    Log.e("Exception", "File write failed: " + e.toString());
} 
}
private String readFromFile() {

String ret = "";

try {
    InputStream inputStream = openFileInput("config.txt");

    if ( inputStream != null ) {
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        String receiveString = "";
        StringBuilder stringBuilder = new StringBuilder();

        while ( (receiveString = bufferedReader.readLine()) != null ) {
            stringBuilder.append(receiveString);
        }

        inputStream.close();
        ret = stringBuilder.toString();
    }
}
catch (FileNotFoundException e) {
    Log.e("login activity", "File not found: " + e.toString());
} catch (IOException e) {
    Log.e("login activity", "Can not read file: " + e.toString());
}

return ret;
}

but for each object you have to create separate file with different name.

hope this will help you..

Answer 3

below is way to store data in android:

• shared preferences(data will keep until user uninstall the app or clear the app cache in setting application manager)
• sqlite(permanent storage)
• create a file to store(permanent storage) or if your data doesn't need to store permanently you may just create a singleton class to store your data. the data stored will gone after user close the app.

Answer 4

 public void Save(String fileName) {
    try {
        OutputStreamWriter out = new OutputStreamWriter(openFileOutput(fileName, 0));
        out.write(EditText1.getText().toString());
        out.close();
        Toast.makeText(this, fileName + " saved!", Toast.LENGTH_SHORT).show();
    } catch (Throwable t) {
        Toast.makeText(this, "Exception: " + t.toString(), Toast.LENGTH_LONG).show();
    }
}