I am given a JSON array with some values being empty. Instead of null, these values are currently just empty, which makes the JSON invalid. For example:
[
"Name",
,
"card",
,
,
342,
2334,
0
]
If possible, I'm looking for a regular expression to replace the empty space with null:
[
"Name",
null,
"card",
null,
null,
342,
2334,
0
]
The new lines and indentation are not present in the actual JSON.
Try replacing any empty string or whitespace preceded and followed by a comma (or by [ or ] if it occurs exactly at the beginning or end of the list) with null.
It should work whether the actual JSON string has whitespace or not.
String result = str.replaceAll("(?<=,|\\[)\\s*(?=,|\\])","null")
null? Shouldn't it be replaced by "null,"?
Note: This works if you have whitespace like in your OP. Otherwise, you'll want to use @anana's answer or @BillCriswell's comment.
Replace:
^(\s*)(?=,)
With:
$1null
This looks at the beginning of each line (^), followed by capturing 0+ whitespace characters ((\s*)), while looking ahead to see that the next character is a comma ((?=,)).
This will need to be a global match (g modifier) and, depending on the language, you may need to make ^ match each new line (m modifier).
Example: Regex101
,,=>,null,and,]=>,null]?,,,? It would replace it with,null,,but there would still be two consecutive commas left.