Android EditText with space every 4 characters

BankCardNumberEditText.java

//Util methods
public static void editTextSetContentMemorizeSelection(EditText editText, CharSequence charSequence) {
      int selectionStart = editText.getSelectionStart();
      int selectionEnd = editText.getSelectionEnd();
      editText.setText(charSequence.toString());

      if (selectionStart > charSequence.toString().length()) {
          selectionStart = charSequence.toString().length();
      }
      if (selectionStart < 0) {
          selectionStart = 0;
      }

      if (selectionEnd > charSequence.toString().length()) {
          selectionEnd = charSequence.toString().length();
      }
      if (selectionEnd < 0) {
          selectionEnd = 0;
      }

      editText.setSelection(selectionStart, selectionEnd);
  }

public static String formatStrWithSpaces(CharSequence can) {
  StringBuffer sb = new StringBuffer();
  for (int i = 0; i < can.length(); i++) {
      if (i != 0 && i % 4 == 0) {
          sb.append(' ');
      }
      sb.append(can.charAt(i));
  }

  return sb.toString();
}

//main
edit.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        String origin = s.toString().replaceAll(" ", "");
        String formatStr = formatStrWithSpaces(origin);
        if (!s.toString().equals(formatStr)) {
            editTextSetContentMemorizeSelection(edit, formatStr);
            if (before == 0 && count == 1 && formatStr.charAt(edit.getSelectionEnd() - 1) == ' ') {
                edit.setSelection(edit.getSelectionEnd() + 1);
            }
        }
    }

    @Override
    public void afterTextChanged(Editable s) {
    }
});

初始粘贴非格式化字串时光标的位置有点小问题