int n = 0;

try {
    n = Integer.parseInt("21"));
} catch(NumberFormatException e) {
   System.out.println("Could not parse " + e);
} 
// int to string
String s = String.valueOf(24);

String sFileContent = readFile("myfile.txt",StandardCharsets.UTF_8);

	static String readFile(String path, Charset encoding) 
		  throws IOException 
		{
		  byte[] encoded = Files.readAllBytes(Paths.get(path));
		  return encoding.decode(ByteBuffer.wrap(encoded)).toString();
		}

// write file
String sOut = "text blah hello world etc.";
		writeToFile(sOut"someName.txt");	
	static void writeToFile(String sB,String name) {
		String folder = ("c:\\folder\");
		File f = new File(folder+ name);
		BufferedWriter writer = null;
			writer = new BufferedWriter( new OutputStreamWriter(
                           new FileOutputStream( folder+name),"UTF-8"));
			writer.write( sB);

				if ( writer != null)
					writer.close( );
	}

    public static class YourFragment extends Fragment {
    //you have to add constructor!!!!!	
    public YourFragment(){}

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View view = inflater.inflate(R.layout.activity_main, container, false);

            return view;
        }   

    }