无法在内部存储中创建文件

Question

i am trying to create a file in the internal storage, i followed the steps in android developers website but when i run the below code there is no file created

please let me know what i am missing in the code

code :

File file = new File(this.getFilesDir(), "myfile");
    try {
        file.createNewFile();
    } catch (IOException e) {
        e.printStackTrace();
    }
    FileOutputStream fOut = null;
    try {
        fOut = openFileOutput("myfile",Context.MODE_PRIVATE);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    try {
        fOut.write("SSDD".getBytes());
    } catch (IOException e) {
        e.printStackTrace();
    }
    try {
        fOut.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 1

默认情况下，这些文件是私有的，只有您的应用程序可以访问并在用户删除您的应用程序时被删除

Answer 2

For saving file:

public void writeToFile(String data) {
    try {
        FileOutputStream fou = openFileOutput("data.txt", MODE_APPEND);
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fou);
        outputStreamWriter.write(data);
        outputStreamWriter.close();
    }
    catch (IOException e) {
        Log.e("Exception", "File write failed: " + e.toString());
    }
}

For loading file:

public String readFromFile() {

    String ret = "";

    try {
        InputStream inputStream = openFileInput("data.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;
}

Answer 3

Try to get the path for storing files were the app has been installed.The below snippet will give app folder location and add the required permission as well.

 File dir = context.getExternalFilesDir(null)+"/"+"folder_name";

If you are handling files that are not intended for other apps to use, you should use a private storage directory on the external storage by calling getExternalFilesDir() . This method also takes a type argument to specify the type of subdirectory (such as DIRECTORY_MOVIES). If you don't need a specific media directory, pass null to receive the root directory of your app's private directory.

Probably, this would be the best practice.

Answer 4

Use this method to create folder

public static void appendLog(String text, String fileName) {
    File sdCard=new File(Environment.getExternalStorageDirectory().getPath());
    if(!sdCard.exists()){
        sdCard.mkdirs();
    }
    File logFile = new File(sdCard, fileName + ".txt");
    if (logFile.exists()) {
        logFile.delete();
    }
    try {
        logFile.createNewFile();
    } catch (IOException e) {
        e.printStackTrace();
    }
    try {
        //BufferedWriter for performance, true to set append to file flag
        BufferedWriter buf = new BufferedWriter(new FileWriter(logFile, true));
        buf.write(text);
        buf.newLine();
        buf.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

In this method, you have to pass your data string as a first parameter and file name which you want to create as second parameter.