Android说无法解析方法'getExternalFilesDir（null）'

Question

I am using Android Studio to try to write a file to external storage.

Other posts have recommended I do this using getExternalFilesDir(null) , but I get the message Cannot resolve method 'getExternalFilesDir(null)' .

 public void makeFile() {
    try {
        String storageState = Environment.getExternalStorageState();
        if (storageState.equals(Environment.MEDIA_MOUNTED)) {
            File file = new File(getExternalFilesDir(null), "outputFile.txt");
            FileOutputStream fos = new FileOutputStream(file);
            String text = "Hello, world!";
            fos.write(text.getBytes());
            fos.close();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

I haven't been able to find any way to get rid of this error. Thanks in advance for any solutions to the problem.

Answer 1

getExternalFilesDir() is method which requires Context . In Activity class you just need to call getExternalFilesDir() , but in other classes you need to call it with Context .

Like:

• getActivity().getExternalFilesDir(null) in Fragment

• context.getExternalFilesDir(null) in classes, where you pass Context as parameter

• YourActivity.this.getExternalFilesDir(null); when called in inner class of Activity