Using RegEx to change the date with string inbuilt function in java

I have a below code where I need to replace all “buyDate:YYYY-mm-dd” to current date using String.replaceAll method. Any suggestion how I can update date for only buyDate field, since I have some other date field so I cannot directly perform replace operation.

String str = content .replace("yyyy-mm-dd",;

I am using loading below data to string object which is stored in json file.

Json file:

    "id": 123,
    "test": {
        "id": "1",
        "name": "string"
    "items": [
            "id": "123",
            "product": {
                "id": "12345",
                "buyDate": "2019-04-15",
            "Moreitems": [
                    "id": "qwerty123",
                    "product": {
                        "id": "qwerty345",
                        "buydate": "2019-04-15",


You need to use a regular expression to match the search pattern. You can learn more about how to write regular expressions at


  • s matches a white space character
  • d matches a digit
  • * means match the preceding token 0 or more times
  • {4} means match the preceding token exactly 4 times

The regular expression that matches a date is: d{4}-d{2}-d{2}. It means match four digits followed by dash then two digits then a dash then two digits.

Of course you need to escape the back-slack when you are writing a string literal in java. You also need to escape the double quotes.

String result = content.replaceAll("("buyDate"\s*:\s*"(\d{4}-\d{2}-\d{2})")", ""buyDate":" + + """);

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