Simple way to add double quote in a JSON String

Question

I am trying to write something that returns some search suggestion result.

Suppose I have an string like this :

"[Harry,[harry potter,harry and david]]"

The format is like [A_STRING,A_STRING_ARRAY_HERE].

But I wany the output format to be like

[ "Harry",["harry potter","harry and david"]]

so that I can put it into the HTTP Response Body.

Is there a simple way to do this, I don't want to add "" for a very single String from scratch .

Answer 1

Demo

String text = "[Harry,[harry potter,harry and david]]";
text = text.replaceAll("[^\\[\\],]+", "\"$0\"");

System.out.println(text);

Output: ["Harry",["harry potter","harry and david"]]

---

Explanation:
If I understand you correctly you want to surround series of all non-[-and-]-and-, characters with double quotes. In that case you can simply use replaceAll method with regex ([^\\[\\],]+) in which which

• [^\\[\\],] - represents one non character which is not [ or ] or , (comma)
• [^\\[\\],]+ - + means that element before it can appear one or more times, in this case it represents one or more characters which are not [ or ] or , (comma)

Now in replacement we can just surround match from group 0 (entire match) represented by $0 with double brackets "$0". BTW since " is metacharacter in String (it is used to start and end string) we need to escape it if we want to create its literal. To do so we need to place \ before it so at the end it String representing "$0" needs to be written as "\"$0\"".

For more clarification about group 0 which $0 uses (quote from https://docs.oracle.com/javase/tutorial/essential/regex/groups.html):

There is also a special group, group 0, which always represents the entire expression.

Answer 2

If the format [A_STRING,A_STRING_ARRAY_HERE] is consistent, provided that there are no commas in any of the strings, then you can use the comma as a delimiter and then add the double quotes accordingly. For example:

public String format(String input) {
    String[] d1 = input.trim().split(",", 2);
    String[] d2 = d1[1].substring(1, d1[1].length() - 2).split(",");
    return "[\"" + d1[0].substring(1) + "\",[\"" + StringUtils.join(d2, "\",\"") + "\"]]";
}

Now if you call format() with the string "[Harry,[harry potter,harry and david]]", it would return the result you want. Not that I used the StringUtils class from Apache Commons Lang library to join the String arrays back together with a delimiter. You can do the same with your own custom functions.

Answer 3

This peace of program works (you can optimize it):

//...
String str = "[Harry,[harry potter,harry and david]]";

public String modifyData(String str){

    StringBuilder strBuilder = new StringBuilder();
    for (int i = 0; i < str.length(); i++) {
        if (str.charAt(i) == '[' && str.charAt(i + 1) == '[') {
            strBuilder.append("[");
        } else if (str.charAt(i) == '[' && str.charAt(i + 1) != '[') {
            strBuilder.append("[\"");
        } else if (str.charAt(i) == ']' && str.charAt(i - 1) != ']') {
            strBuilder.append("\"]");
        } else if (str.charAt(i) == ']' && str.charAt(i - 1) == ']') {
            strBuilder.append("]");
        } else if (str.charAt(i) == ',' && str.charAt(i + 1) == '[') {
            strBuilder.append("\",");
        } else if (str.charAt(i) == ',' && str.charAt(i + 1) != '[') {
            strBuilder.append("\",\"");
        } else {
            strBuilder.append(str.charAt(i));
        }
    }
return strBuilder.toString();
}