Improve permission string & cleanup code

    <string name="welcome_msg">Welcome to the CyanogenMod file manager.\n\nThis app allows you to explore the file system and do operations that could break your device. To prevent damage, the app will start in a safe, low-privileged mode.\n\nYou can access the advanced, full-privileged mode via Settings. It\'s your responsibility to ensure that an operation doesn\'t break your system.\n\nThe CyanogenMod Team</string>

    <string name="activity_not_found_exception">Couldn\'t find an app to open this file</string>

    <string name="storage_permissions_denied">Storage permissions denied!</string>

    <string name="storage_permissions_denied">The app cannot run without permission to write to external storage.</string>

</resources>

import android.database.Cursor;

import android.graphics.Color;

import android.graphics.drawable.Drawable;

import android.Manifest;

import android.net.Uri;

import android.nfc.NfcAdapter;

import android.nfc.NfcEvent;

    private static final int REQUEST_CODE_STORAGE_PERMS = 321;

    private boolean hasPermissions() {

        String permission = "android.permission.WRITE_EXTERNAL_STORAGE";

        int res = checkCallingOrSelfPermission(permission);

        int res = checkCallingOrSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE);

        return (res == PackageManager.PERMISSION_GRANTED);

    }

    private void requestNecessaryPermissions() {

        String[] permissions = new String[] {

                "android.permission.WRITE_EXTERNAL_STORAGE"

                Manifest.permission.WRITE_EXTERNAL_STORAGE,

        };

        requestPermissions(permissions, REQUEST_CODE_STORAGE_PERMS);

    }