Bagaimana untuk Menyahlepaskan Literal Rentetan Java dengan Berkesan?

public static String unescapeJavaString(String oldstr) {
    // Initialize variables
    StringBuilder newstr = new StringBuilder(oldstr.length());
    boolean saw_backslash = false;

    for (int i = 0; i < oldstr.length(); i++) {
        int cp = oldstr.codePointAt(i);

        // Handle UTF-16 code units
        if (oldstr.codePointAt(i) > Character.MAX_VALUE) {
            i++;
        }

        // Process characters
        if (!saw_backslash) {
            if (cp == '\') {
                saw_backslash = true;
            } else {
                newstr.append(Character.toChars(cp));
            }
            continue;
        }

        // Handle backslash sequences
        if (cp == '\') {
            saw_backslash = false;
            newstr.append('\');
            newstr.append('\');
            continue;
        }

        // Handle specific escape sequences
        switch (cp) {
            case 'r':
                newstr.append('\r');
                break;
            case 'n':
                newstr.append('\n');
                break;
            case 'f':
                newstr.append('\f');
                break;
            // Handle other escape sequences as needed
            // ...
        }

        saw_backslash = false;
    }

    // Append any remaining characters
    if (saw_backslash) {
        newstr.append('\');
    }

    return newstr.toString();
}