将一系列数字从字符串转换为不同的数字

Question

Pretty much what I need to happen, is I need to take a string

Example

 String ln = "It's so pretty! �";

The idea, is we're taking this string, a converting the end of the line..

�

into

🀽

I can convert that easy enough, but the problem there can be multiple numbers to change. The string could be...

 String ln = "It's so pretty! �� But � �";

And I need to convert, every number in that line..

The purpose of this, is each one of those codes, is unicode for a character, but it's shorthanded, and not correct for the purpose that I need it to be.

• Every number is in the same format.. and will always be 5 characters long.
• Every code, starts with "&#" and ends with a semicolon.
• Every code, can be anywhere in the string

When I tried to create a method to convert the numbers, I pretty much split the string on "&#" and it works, for every case, except for when they aren't connected in series. For example,

String ln = "Gahh it's so pretty. ������";

It will solve that string, and convert all the numbers, and can recreate the string as it was originally, just with modified numbers. But it wouldn't recreate a string, with a gap in between number codes.

---

This is the code I have used.. like I said, it converts like its supposed to, just only in one case, and I haven't figured out how to make it work on all cases.

public static void main(String args[]) {
    String ln = "Gahh it's so pretty. ������";
    //71680 + code present
    //Gahh it's so pretty. ������
    String tmp = ln;
    String[] codes = tmp.split("&#");
    System.out.println(ln);
    ArrayList<Integer> ids = new ArrayList<>();

    for (int i = 0; i < codes.length; i++) {
        codes[i] = codes[i].trim();
        if (codes[i].length() != 6)
            continue;
        if (codes[i].endsWith(";")) {
            codes[i] = codes[i].substring(0, codes[i].length()-1);
        }
        try {
            ids.add(Integer.parseInt(codes[i]) + 71680);

        } catch (NumberFormatException e) {
            System.err.println("Error in conversion: " + codes[i]);
        }
    }
    //System.out.println(Arrays.toString(codes));

    codes = tmp.split("&#\\d{5}");
    //System.out.println(Arrays.toString(codes));
    for (int i = 0; i < codes.length; i++) {
        //System.out.println(codes[i]);
        if (codes[i].equals(";")) {
            codes[i] = "&#"+ids.remove(0)+";";

        }
    }
    for (String s : codes)
        System.out.print(s);
    System.out.println();

}

I just need some input on this. If you're willing to correct a few things, I'd gladly accept the help, but honestly, I'm more interested in how you would approach this problem.

Answer 1

You should look into Regular Expressions

 Pattern pattern = Pattern.compile("&#(\\d+);");

should work to find all the numbers in your string. The Matcher objects also have methods start() and end() to get the offsets of the matches so you can use those to make substrings to help build up your new String

Answer 2

You can use the look ahead/behind regex: "(?<=&#)(\\\\d+)(?=;)" to match and replace.

    String ln = "Gahh it's so pretty. ������";

    Pattern patt = Pattern.compile("(?<=&#)(\\d+)(?=;)");
    Matcher mat = patt.matcher(ln);
    StringBuffer buf = new StringBuffer();
    while(mat.find()) {
      mat.appendReplacement(buf, Integer.toString(Integer.parseInt(mat.group(1)) + 71680));
    }
    mat.appendTail(buf);

    System.out.println(buf.toString());

Answer 3

With Regex , using Matcher and Pattern you can construct a pattern as so:

"&#(\\d{5});\\s?"

This will match your codes that may or may not be followed by a space. The numbers of the code are captured into group 1 which you can apply your modifications to. Then replace each code with the new code like so:

public static void main(String[] args) throws Exception {
    List<String> lines = new ArrayList() {{
        add("It's so pretty! &#55357;");
        add("Gahh it's so pretty. &#55357;&#56845;&#55357;&#56845;&#55357;&#56874;");
        add("It's so pretty! &#55357;&#56357; But &#55468; &#55357;");
    }};

    for (String ln : lines) {
        Matcher matcher = Pattern.compile("&#(\\d{5});\\s?").matcher(ln);
        while (matcher.find()) {
            int number = Integer.parseInt(matcher.group(1)) + 71680;
            ln = ln.replace(matcher.group(0), "&#" + number + "; ");
        }
        System.out.println(ln);
    }
}

Results:

It's so pretty! 🀽 
Gahh it's so pretty. 🀽 😍 🀽 😍 🀽 😪 
It's so pretty! 🀽 🐥 But 🂬 🀽 

As you can see, spaces are added after each code.