void (int caretOffset, Document document, String fileText, char c) { if (caretOffset < fileText.length() && fileText.charAt(caretOffset) == c || caretOffset > 0 && fileText.charAt(caretOffset - 1) == c) { document.insertString(caretOffset, new CharArrayCharSequence(c, c)); } else { document.insertString(caretOffset, new CharArrayCharSequence(c, c, c)); } }