Intent importIntent = new Intent(Intent.ACTION_GET_CONTENT);
        importIntent.setType("file/*");
        startActivityForResult(importIntent, ACTIVITY_REQUEST_CODE_IMPORT);

Intent importIntent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
importIntent.addCategory(Intent.CATEGORY_OPENABLE);
importIntent.setType("*/*");
startActivityForResult(importIntent, ACTIVITY_REQUEST_CODE_IMPORT);