A somewhat silly task.

code snippet

  File someFile = new File("some_file.txt");
  Charset someCharset = Charset.forName("windows-31j");
  byte[] bytes1 = FileUtils.readFileToByteArray(someFile);
  String content1 = new String(bytes1, someCharset);
  byte[] bytes2 = content1.getBytes(someCharset);
  boolean isValid = Arrays.equals(bytes1, bytes2);